As others have said, RV ownership is not a "cheap" way to live and an expensive hobby if you are not a full timer.
Your RV expenses for the RV will be:
Your RV loan
Your RV (specific RV) insurance
Your RV License Plates / Title / DMV registration to legally use it on the road
Fuel for traveling
Campsite costs
Insurance to maintain on your tow vehicle (with a rider for your trailer)
License Plates / title / registration for your tow vehicle
Loan on your tow vehicle
Propane fill-ups for the RV
Maintenance and repair costs for the RV (and you will have them)
If you are looking for a "cheaper" way to live, an RV is NOT the way. It is as expensive (or more) than renting or purchasing an apartment (or in some cases, buying a house).
There are no tax write-off's for an RV, (none I've ever been able to find, although some say an RV can be treated like a second home ... it's never worked out that way for me ... per H&R Block ... and they are the experts).
Then if traveling on the road, you always have the risk of mechanical failure, breakdowns, collisions, and of course ... traffic fines if you speed or disobey the laws on the road.
Don't get me wrong though. If it were financially impossible to do all this, none of us would own an RV. All I'm saying is ... it's not a "cheap alternative" to a sick-and-brick house. It will cost as much (or maybe even more), depending on your specific lifestyle.
But to get back to your original question. If you are parking the trailer full time, you would be much better to get a Park Model and park it in a conventional Mobile Home park. In the long run, it will be cheaper than maintaining an RV and you'll have the full hook-ups. And you can winterize the unit based on the location you settle on, and it will fit the Mobile Home park style. Whereas, skirting a travel trailer in a more conventional campground may not be acceptable.
If parked full time in one location, you'll need better water hook-ups than simple garden hoses running from a spigot and your sewer connections will need to be more permanent also. Flexible vinyl sewer hoses won't hold up the duration of time. You'll need to attach PVC piping or something more permanent from your tanks to the park supplied sewer system.
If you are parking the camper permanent in one spot, there is no need for a large tow vehicle. Work out a deal with the dealership to have the trailer delivered to your permanent spot and you won't need a truck at all.
However, if you do plan on traveling from location to location and need the tow vehicle, I suggest getting the truck first so when you buy the trailer, you've got something to tow it from the very beginning, and can also get the proper hitch work done immediately.
By the way, if you get an F350, or 3500 (GM or Dodge), you'll have plenty of truck to tow pretty much anything in the range you are considering. If you REALLY want stable towing, consider a dually, and if really want "power" make it a diesel. If you are towing a lot ... your choice for an F350 / 3500 dually diesel will never be a regret.
Here again, if really parking permanent ... trailer first, no need for a truck.
If towing and moving ... truck first, then trailer.