Need Full-Time Solution

For tts, check out the Open Range Roamer and Open Range Mesa Ridge lines. they are pretty well insulated. I think you will find that most rvs will not stand up to Alaska winters without help.

We have survived temps below freezing in our Jayco (insulated but not heated underbelly) and our Sprinter (heated and insulated underbelly, cousin to the Outback) though not in either for extended periods of time (more than four days). Neither sustained damage but the Sprinter was better on propane use.

My choice would be a large 40' plus, diesel pusher and tow a car.

It will be a bit crowded with either of your options.

Mine has a nice bathroom, shower, washer/dryer, central vacuum, 12' side by side refer/ ice maker, 2 tv, 2 furnaces, and 2 air conditioners, large heated tanks and 8 KW generator plus 3 burner gas stove. Made for all seasons.

I've seen some nice 40' plus 5th wheels as well.

Here are my suggestions or input:

As for traveling in colder weather, I would go north when it's warm and go south when it's cold. People do camp and live in cold weather with an RV, but make it easier on yourself, the wife, the dogs, the three small kids and don't do it. You get into heated water lines, skirting the RV so your sewage lines don't freeze and your furnaces are going to use a ton (several tons) of propane. Even four season RV aren't really designed to live in full time during a cold winter. They're good for a skiing or snowmachining vacation. You really aren't going to do much sightseeing or touristy things (they'll all be closed) at below zero temps.

As for towing a toad behind a MH, there's been a lot of discussion on the forum about that. Most people don't notice it back there and it makes less than a 1/2 MPG differance if that much. Don't let the fuel milage be a deciding factor on towing a toad. Unless you're talking a small MH and a large toad, the mountains aren't going to make it difficult to tow a toad. If you buy a 5th wheel or TT and tow it with a truck, you're going to burn more fuel driving it as a daily driver than you'll use towing a toad behind a MH.

You'll need a generator whether it's built in or carried seperatly. If you buy a truck to pull TT without a generator, then the generator (and extra gas cans) will be in the back of the truck with the dogs.
Maybe you can get a two part shell custom built, but that's going to be expensive. Don't forget to build a heater and air conditioning into the canapy somehow to keep the dogs warm /cool if they're not riding in a nice warm (cooler) MH.

With the kids and dogs, I think you'll be much better off with a MH and toad. If there's a floorplan in a TT or 5th wheel that works, then there has be be one in a MH. Make life easier on yourself. Go with a MH and the weather.

***And get something with a washer and dryer or else you're going to spend a lot of time sitting in a laundramat.
Bill

Ditto X2 on the MH. Been there done that and MH is the way to go.
Take off RV'ing without towing a car.

I full timed for 2 years without a toad. There really is not that many places site seeing that you can't take a MH to. Most have parking for RV's. Going into town? I haven't seen a MH yet that didn't fit in a grocery store parking lot.

Later on find an inexpensive used lightweight car to tow. IMHO too many people think you have to go out and buy a brand spanking pricey new toad to go RV'ing. I bought mine with full intentions of it being just a used car to tow around if I needed it and selling it when I was done full timing.

RE: your idea on a truck with bed cover for the dogs.
Dogs in a covered truck bed will heat stroke dead in seconds in summer and freeze to death in winter. RV'ing this way with dogs will be your biggest problem and ruin your RV'ing time with the family.
Just saying. Good luck finding just the right RV for you and your family.

The difference in mileage when towing a vehicle behind a motorhome is negligible. For your needs, a moho may be your best solution, IMO.

Keeping warm in Canada and Alaska during the winter is a whole different story. No matter what you hear about well insulated RVs, keeping warm inside and keeping the tanks from freezing can be a challenge and also a big expense.

Good luck!

Just a thought, I don't know of any state where it's illegal to put dogs inside a FW or TT. I'd think they would be quite comfortable if they were in a dog crate and the crate was secured so it couldn't slide around.

At this point I don't think brands are important. When you look at RVs of any kind. You need to check out, are the fresh, grey and black tanks heated. Usually heat comes from the furnace into that area. Next, where are the dump valves? Cold weather RVs have the dump valves located into the heated area. Valves do freeze. When the dump valves are in the heated areas there is long extentions on the valve handles that extend out of the heated areas. If you look at RVs and you see dump valves in the open it is not a cold weather type RV. Just some thoughts. You could think about a toy hauler. Great place for dogs, plus a work area etc. Dogs in the RV while traveling is not a good idea. I'm not a 5ver fan. Been there done that, but this is about what may be best for you. Others may have many more ideas. I have found that camping in temps below 10 degrees F is questionable in any RV. JMHO from living in Wyoming and traveling in the winter times quite a bit. However, I blow out my water lines and empty tanks when the temp drops below 10 degrees F. then de-winterize when temp warms up. I just use air to blow out my lines. When it is cold I use RV anti-freeze to flush toilet etc. I don't want those dump valves to freeze. This is some very basics. As you look at RVs you will start to see more of what you need for cold weather.

A van is a viable option as a TV for a TT. The length of a TT is going to be a real killer for a family of four. A sufficiently large TT is going to require a lot of TV. I know you may not like to hear this, but consider adopting at least two of the dogs out and stick with the fifth wheel option. At least with a fifth wheel you can get a nice bunk house version.

From what you explained here, I would think a motor home with a toad is the best by far. JMHO. The kids and dogs make it a easy choice. I have a 5th wheel and Truck camper but use to have a class C motorhome. The motor home was great for kids and our dog. But if between a 5th wheel or TT I would go with the 5th for storage space.