How about a Chrysler Imperial of the '63-'64 vintage?
There are few cars more comfortable than these, in terms of both ride comfort and interior space.
Negatives: Very poor fuel economy, difficulty in finding one in good mechanical condition
Positives: Unequalled passenger comfort, body/chassis that is virtually indestructible
If they are worried about fuel costs, they could even get a class B motorhome, which is little more than a conversion van with some amenities.
The only question I have about this idea is, what kind of motorhome can you get for $8,000? The only motorhomes I have seen that cheap were made decades ago and I would not trust them to be reliable.
I’m surprised nobody has mentioned the full size FWD Buicks yet. The Lesabre/Park Avenue is hard to beat for this kind of driving. It’s a large, comfortable, powerful car with a huge trunk, seats five or six adults comfortably, has a really soft ride, is quiet as a tomb on the highway, gets 30mpg, and can be serviced by any mechanic anywhere. Plus, they’re usually driven and maintained by the AARP set. In fact, just a few years ago, Buick was second in initial quality ratings by Consumer Reports, if I remember correctly. I think they got beat out by Lexus, but were ahead of Honda and Toyota. That’s pretty remarkable coming from a publication that is consistently biased towards the Japanese automakers, and has been consistently for the last twenty years ago. Seriously, though, you would be a fool not to consider a LeSabre/Park Avenue.
Regarding a motorhome I’d like to add that your overall cost will be very similar if you take a car and stay in motels vs sleeping in a motorhome and paying much more for gasoline. This comparison will not be quite as valid if you pay to stay in campgrounds but free of charge dry camping in WalMart parking lots was permitted some time back; I don’t know what the current policy is.
Living in a motorhome has its limits so once in a while you will want to take a break and stay in a motel.
We have also dry camped in truck stop parking lots for no charge but would buy a fill of gasoline as a courtesy while asking permission which was never denied. I recall being instructed to find a spot away from the idling trucks at one truck stop. Highway rest stops do not typically permit overnight camping but you can stay 4 hours and then move on.
Traveling in a motorhome proved to be very safe for us. When going down a two lane road I would frequently see vehicles coming from the opposite direction move over in their lane to make plenty of room for us.
Yes, motorhomes can be lots of fun. I remember tent camping in Alaska in the rain, looking over to the folks drinking coffee and playing cards in the motorhome across from us - very nice! Big question for OP - what do you want to do at your destinations? Are you planning to spend time in cities? If so, motorhome would be tough. But we’ve not heard from Theo - what’s up???
Some towns have outlawed dry camping at Walmart, but generally, as long as there are no signs forbidding it, and you get permission from the manager, you can still do it.
Flying J and some other truck stop chains cater to RVers. The only bad thing about Flying J is that their restaurant food is terrible. If you want a steak, it has to be well done, and the food on the buffet can sometimes look and taste like it has been there for days. Some truck stops actually have decent food. If you go the RV route, buy a truck stop guide at the first truck stop you can find that sells them. They only cost a few dollars and they will really help you plan your stops if you are on a budget.
I will reiterate that if you buy any motorhome for less than $8,000, you better budget for repairs.
My recommendation would be based on info that you have not provided; any camping out, terrain traveled (gravel mountain pass for example), and just how much junk you’re wanting to drag along.
If the trip involves hauling along a bunch of stuff (which I assume it does based on a summer of driving and the mileage) then I’d agree with a full size truck with a camper shell recommendation.
Just my opinion, but planning to put this kind of mileage on a vehicle during the summer would not be an enjoyable trip. The sights are made to be looked at and enjoyed; not quickly snap a pic and hit the road or take a pic through the window at 80 MPH.
Do the math. If you do 300 miles PER DAY for each and every day of a 90 day summer period that amounts to 27k miles and that’s going to get old quick. Start talking about 30-40k miles and the number goes much higher.