Here's a design that I have been working on for a while. It started out as an idea of designing a TTT for the Northern Tools 5x8 trailer but it has changed a bit since then. My idea was to have the smallest TT while still having all of the amenities of a larger trailer while not feeling really cramped.
Specs:
Box length: 12'-6"
Box width" 7'-3"
Interior Height: 6'-6"
Features:
Dry bath with 32"x32" shower and toilet
L-shaped dinette/seating that converts to a twin OR queen bunk
Large kitchen area with stove, sink and lots of counter space
Lots of storage