Hi, I'm going to suggest something a little different, just to give you something to think about. We were where you are now with our family of 5 (with one on the way) 14 years ago.
Our Class A rig has seatbelts for 12 (3 on each of two sofas, 4 dinette, driver & passenger). While it's rare to have that many, it's not unheard of, and you can always add them on your own. We have slept 8 & 9 in our rig several times using sleeping bags on the floor...plus two 45 pound dogs. Were we cozy? Sure, but it worked. A tent, if you kids are old enough and wish to use one, would be even better. And our Class A now could probably be purchased (used, of course) for less than the cost of a new Nissan NV (a VERY neat vehicle, by the way, was unaware of them until this thread).
Now it's fairly common to find class A's with bunk beds, plus sofa and dinette for sleeping and a queen bed in back. So sleeping 8 is doable.
I'm just suggesting that you might be able to find a used Class A rig which will accommodate your family and not break the bank. Of course, you'd also have to figure out how to tow a dingy for 8 people. But many cars can be rigged to tow with some work. Of course, one large enough for 8 will exceed the towing capacity of most gas motorhomes, so you'd most likely be looking at diesels with sufficient tow capacity.
There are also some "Super-C's" on the Chevy 5500 Chassis which might even be a better option with their cab-over beds. These were coming out right after we purchased our rig (2005-ish). So you might be able to pick one up for a decent price.
Not sure if you considered this, I know when we started looking for our family of 6, we were looking at towables and tow vehicles. Now, going on our 13th year in our Class A, we know we made the right decision to get the Class A and tow our minivan. It's just so much easier to travel...ESPECIALLY with children.
Do you have an approximate budget for your purchase(s)? What type of vehicle do you have now to fit your family? What are the ages/sizes of your family members? You want to make sure you find a solution that will work as they grow.
Most important, take your time and do your research...it WILL pay off. Buying the wrong vehicle/RV can be an expensive learning lesson. But to research and know what you want BEFORE you put your money down. We spent about 2 years researching...starting off with pop-ups and hybrids to tow with our Odyssey and researching everything in between up to the gas Class A's, which we ultimately decided was best for us.
Good Luck in your search,
~Rick
2005 Georgie Boy Cruise Master 3625 DS on a Workhorse W-22
Rick, Gail, 1 girl (27-Angel since 2008), 1 girl (22), 2 boys (23 & 20).
2001 Honda Odyssey, Demco Aluminator tow bar & tow plate, SMI Silent Partner brake controller.