There is no way that spending the amount of money you are going to spend for a truck camper AND a Truck is smart.
There are SO MANY class C's in the 26' and under class (new enough to be an E450 (PERFECT for towing) its CRAZY to spend 3x that for a truck/camper.
I just did Yellowstone area for 3 weeks last summer and there were a TON of smaller Class C's out West!!!!
Just think of the convenance of driving, stopping, lunching, driving....without having to get out and drag the dog around. Not every day out West is Sunny! It rains, snows, freezes.....
$25-35K ...... done. Good luck finding a Truck and camper for under $75K that aren't a piece of shizzle.
Good luck with your decision.
Last note.....If you want to spend more and unlike the whiner complaining about lack of quality in the "insulation", then buy a Bigfoot Class C and you WILL BE comfortable in cold wx.