Well, I'll offer up my opinion, worth what u pay for it.
I'm reasonably mechanically inclined but have no desire to restore a wreck. I just bought this for $11k. At the time I thought I paid a bit much, but turns out a decent deal. Has 30k on it when I bought it, almost new inside, bathroom, stove, fridge, heater, onan generator, same stuff as a roadtrek. 1998 coachmen, 18 ft long.
Bed and dinette in back, about a full size, maybe a little larger. Bubble top is an extra bed or great for storage. I put a solar panel on it as well. I use it to meet up and camp with dirt biker friends. It has seen some tough roads, winds, rain. I've had many rv's.
Having driven roadtrek dodges and Chevys, pleasure way fords, falcons, a couple coachmen and a Phoenix van or two...I've driven all the chassis, like you. Chevy is definitely the most stable. Even older like mine, gmc savanna. Best on bad roads too. Mine has the 5.7L engine, before the 5.3 and 6.0 new stuff. Has the 4L80 transmission as well, almost indestructible. These engines last well over 200k with no real expensive troubles.
That said, I've talked to some owners of Dodge and Ford based chassis. One guy with a Coachman similar to mine and another with a Falcon told me adding a $200 anti sway bar did wonders. Another decided he didn't need the a/c up top, took it out, added solar, pulled out the generator and added a sway bar. Lot cheaper than a 2006! Most modern power plants do a decent job if serviced right. Triton engines are decent as well. You my need to get the plug issue dealt with, but if proactive, no big deal. Just $. Cure is a time cert product Many Ford engine people use. Similar to helicoil but better.
You seem interested in something smaller, mentioning the rt170. I think you should be patient, look for something older, save $$, use where appropriate for repairs. Mine is almost pristine, they are out there. Also, when I was searching, I wasn't happy about the plumbing, tanks and such exposed underneath the roadtreks. If you are going ski bumming, that may be an issue.
Money spent on depreciation of newer stuff doesn't buy anything real, but money spent on a well kept older model may save quite a bit, depreciation has slowed.
Good luck
