Check out some Utube videos on converted cargo trailers. It doesn't have to be real fancy at first and you can change out the build over time.
The no BR thing is your stumbling block on a camper.
I initially was going to use my 10x6x6 enclosed cargo trailer with side door for camping. I insulated the roof and was just going to use a travel potty and hook stuff to the E-track I had installed for cargo tie down. I have snap in 2x4 holders and a piece of plywood over that provided a bed surface with storage underneath. Instead I sold the cargo trailer and bought a Wolf Pup 16BHS. Yes, it has a bathroom, even a little 12" tub in the shower, but it has the 2 bunks and a RV/short queen and cooking/fridge amenities.
The campers in the style size range you are looking at will pretty much all have a BR, even if it has an outside kitchen.
