New project

I got a Harbor freight trailer for almost a steel last week and wanted to a modular system where I could have a flat bed trailer or a camper trailer. My idea is to use roller lines and or my tractor to pick it up and off the trailer when I need it off (I haven't fully worked it all out yet). The main question I had is should I make it wider as it's a 4x8 trailer but I'd like the bed to be a full size bed so I and my girlfriend can have room when sleeping. Very new to this so it's a lot of planning and to get ready for warm weather to build