If you stay with a lighter TC, yes a 3/4 ton truck will do it.
But the $$ difference between a similarly equipped 2500 (or 250) and a 3500 (or 350) is going to be very little. If 1 ton trucks are common where you are, take a good look at one. We are in a rural area and surprisingly our Chevy dealer didn't have one on the lot.
If you stay with a lighter truck camper, the engine and transmission will have no problem pushing it down the road and have good longevity if it is maintained properly. And with a lighter TC, a dually isn't always necessary.
Fuel mileage? Your results will vary, but with our combo- heavy TC on a beefed up Chevy 2500- we get 9-10 mpg and I stay around 55-60 mph.
This is just my opinion- others will add theirs.
BTW, there are some good deals out there if you are looking at 8 or 10+ year old TCs. Like
HERE