Referring to your original post, what you envision is doable. But because you want to tow a trailer, I would suggest the cap, not the camper.
My wife and I drove our 2003 longbed Tundra to Alaska and back, sleeping in a cap. If I recall correctly, it was a SnugTop. I outfitted the cap with two beds, storage tubs, icebox, Coleman stove, and a Porti Potti. We survived with our marriage intact.
If we were to repeat the exercise, we would look for a cap with more headroom - maybe something like a SnugTop Hi-Liner - the more headroom the better. I would spend some time looking for the cap with the most headroom. Because you have such a short bed, headroom is paramount. Good luck!