Don’t lose out on either deal based on the concerns you posted above. Seriously.
If C of G is your biggest concern, pretend I’m totally wrong with what I posted above (I’m not) and that the CG of the camper is an entire foot (12”) behind the rear axle and that the camper weighs 3000lbs.
Do the math and you’ll see it still doesn’t take a lot of weight off the front. Probably less than a diesel adds to the front over a gas engine. And worst case, you said you can/may resell the truck soon anyways so worst case it’s a little floaty in front. (It won’t be.)
And if the camper truly can’t take a 2’ or so cantilever out the back of the bed (cannot say for sure, but very doubtful that will be an issue either), you have a tailgate, use it.