Can you give us a more specific breakdown of the number and sizes of the people you plan to carry?
I can tell you that very few rigs will have 8 seatbelts, let alone 10. Our Class A actually has 12 belted positions (3 on each of the two couches, four at the dinette, driver & passenger). BUT...usually there was one person on each side of the dinette and one on each sofa. Packing three on a couch would be tough, especially now that they're bigger. Two adults on the same side of the dinette for any period of time would be tough, too.
Regardless of the laws, wearing seatbelts when travelling is a smart idea and I would discourage anyone from not using them while in motion.
From what you've posted so far, I think you'd be better off with a 12 or 15 passenger E-350 based van pulling a travel trailer. You won't have the benefit & convenience of a motorhome, but you will all be safely buckled into a vehicle and you could probably find a trailer that would more readily accept the number of people you mentioned than a class A.
For what it's worth, we have a 36', dual slide, dual sofa class A and it works GREAT for the six of us. Traveling with eight would definitely get cramped unless it's just for day trips. Traveling with ten I would only consider for a 1-2 hour trip. People just would not be comfortable for any longer than that.
Also, remember that some people easily get motion sickness and the rear-facing dinette seat, and even the side-facing sofas might not work for them. You know your family dynamics better than I, but that's something else to consider.
Are any of the children still in carseats? A car seat practically takes up about 2 passengers worth of seating space. Do you need storage space for playpens and other "baby support" equipment? When we bought our class A, those were concerns of ours. But like I said, there were only 6 of us. We sometimes travelled with 8, but only on day trips. We slept 9 once, but that included sleeping bags on the floor.
You're going to want/need a vehicle to travel around in once you're camped, and there aren't many that can seat 8-10 people, and those vehicles that CAN do it are too heavy to be towed my most gas class A's and lower level diesel pushers (which often have a 4-5,000 pound towing limit).
Now, if you just want something for travelling, rather than camping, then you might be able to pick up an old tour bus. But seeing as those typically have new selling prices upwards of one million dollars, I think you'll be hard pressed to find one in decent condition in your price range.
I just reread your post and this statement is troubling to me: "We have no experience with rv’ing and money is tight." Especially the last part. RV'ing can be done cheaply, but in my opinion, you need to be prepared and have the resources available to face a very expensive repair bill at any time. If you don't have about $5 grand just waiting to be thrown away on a major repair while you're on the road, you'll need to figure out some way to get things going again should a serious problem arise. Personal loan, credit card, rich relative. But you should have some backup plan. With 8-10 people, even paying out for a week of hotels while the rig is being repaired would get pricey.
Good luck as you do your research. I'm not trying to ruin your dreams, but I have done a fair amount of research on RV's that work for larger families. You see, it took us over two years to find our "ideal" RV beginning back in 2002. We started looking at hybrid trailers to tow behind our Honda Odyssey and investigated just about every option out there within our budget and finally realized a gas Class A with dual sofas & dual slides was what would suit our needs & budget best, and we tow the Odyssey behind us. I credit the fine wisdom of people on this Forum for giving us their real world advice. We were one of the "rare ones" that bought the right RV the first time. That should be your goal, because buying the wrong one can be an expensive lesson.
I know you asked a bunch of other questions in your post, but I'd recommend you rethink your whole gameplan here a bit.
Again, Good Luck. Please, don't let our posts discourage you. Rather, read and think about what we say based upon our experiences. You CAN find a solution, and we don't mind helping!
~Rick
P.S. By the way, if you happen to win the current PowerBall Lottery, let me know. I'm sure we'd be able to find something that would work within THAT budget!!! :-)