HELP! I'm building a custom travel trailer.

I am in the process of converting a 6x10 V-nose cargo trailer into a camper/motorcycle hauler (my needs are a little more modest than yours). Let me suggest you take a look at trailershowroom.com as they can customize to any level you want and you can pick it up at their factory. Definitely have the A/C and windows installed by them for the additional structural required. I am using a sofa/bed unit from blazinbelltech.com as it can even fold up against the wall for more floor space (I put added vertical support at the wall brackets so the wall doesn't take the vertical load). I had it in my van and it made a pretty comfortable bed. I am getting the rear ramp not only for loading purposes but also for ventilation and open-ness (I'm a little claustrophobic).