I have owned different 5 campers; both solid and poptops. We are now in a 5th wheel. It's a step up from any of the campers, but still only 18.5 feet. I know a bunch of you will chuckle as your slides are bigger than my entire unit! We wanted a shorty do keep doing what we are doing.
Most of our camping is industrial backroad activities. We have always liked being able to go down just about any road with the TC, knowing we could always "just turn around". It's a little more complicated with the rig. Sometimes we need to get out and walk the route, but we haven't been scared or stopped by anything yet.
If you find a smaller "light" 5th wheel, there is no reason to go the extra and have dually. I drag our unit around with a Dodge 3500 Cummins 4 X 4 and we don't even know the thing is on the back.
I can drop the 5th faster than I could ever get a camper off the back of any of the trucks. And, feel safer doing it.
As for the Dempster, did it in '81, the second year it was officially open. It's just another gravel road. There is no reason to worry about it. Just take extra spares! So what if there is 300 miles between fuel stops.