Flex between the cab area and bed area is the main issue. Here are a couple of threads of what you are proposing.
https://www.jeepgladiatorforum.com/forum/threads/jeep-wagoneer-spartan-build-7-seater-gladiator.29340/page-7#post-818758...
If you go to a website called wander the West there is a fair amount of info on heaters for campers. One of the big issues is condensation, supposedly the diesel heaters are better at not creating condensation.
Looks great. I have a JKU with a j30 top and the one thing I wish was being able to open the top up over the driver for that "sunroof" affect don't know if you could shorten it to get a Sunrider or freedom style roof on?