When I started looking at pop up truck campers, it seemed like FWC and ATC were the only "off-road" worthy ones, aluminum, welded frames, light weight, etc. So my wife and I went and rented a FWC Grandby flatbed and toured Utah in February where it got down to 4 degrees near Bryce. We had a great time and confirmed that we would truly enjoy traveling by camper. But we also learned we wished it had more insulation and better build materials on the inside compared to a Hallmark we had checked out previously. In the end, I determined there are and have been plenty of people traveling very happily off-pavement in their Hallmarks, Northstars, Bundutec, and even more in FWC so I broadened my search and happily decided on a Hallmark Guanella.
Inside shower - If you're doing a lot of winter traveling where it'd be too cold to setup outside, maybe give it a bit more consideration
Toilet - we have decided to only set up an emergency/night time setup for the night time. Like some of the others, we don't see the appeal of taking care of business in such a small space but recognize its necessary sometimes.
Hot water heater - ours didn't come with it but I wish it had it (ignorant of how much propane it uses)
Good luck on your search and don't be hesitant to investigate other brands, they may be just as capable for your needs, or maybe not!
Richard