You will need some serious upgrades to improve the weight carrying capacity. At a minimum you will need upgraded rear suspension including shocks. You might need a wheel and tire upgrade. You will be pushing it if you want a hardsided camper and also want to tow a Jeep.
You should stick with a smaller unit without slides to keep the weight down. I suggest you look at Northstar. They have a lot of choices for smaller truck campers.
They also feature cassette toilets. I like mine. It will need to be emptied frequently...like every 2-3 days for 2 campers. It can be dumped in an outhouse, household toilet or of course at a dump station.
Personally I would not give up having a shower. With many smaller units the entire restroom is the shower. That works better than you might imagine. I use a squeegee to wipe down the walls afterwards and it dries quickly.