Did you get the one that was listed on eBay recently???
Everyone has their own priorities, but I'd do the following:
Perminant rear bed pushed to 60" wide. If you're spending 8 hours every day laying there - it's worth making comfortable. For me - it's the centerpiece. Can double as a lounge.
Bulkhead next to the door next to the bed (need something there to stabilize the door and keep the trailer from sagging). Maybe put on some wire shelves (the sort meant to be attached to the backs of doors, they're thin with retaining wires).
Front 2-person dinette.
Countertop filling the roadside space between the bed and dinette. Under the counter would go a fridge
and lots of storage space.
Overhead cabinets over the ends and countertop with a shelf over the 'foot' end of the bed (possibly with hanging space below).
Stick a porta-potty inside the dinette.
I wouldn't bother with a sink or stove since I don't want to cook inside the trailer. I do all that stuff outside (put together a boy-scout-style chuck box to hold all the kitcheney stuff).
Course - implicit in the above is the assumption that you're aiming at a 2-person trailer. If specifically laying it out for one, I'd do it differently.