Tell us about yourself!
First, kudo's for doing this project! A lot to tackle, I don't think I have the patience for this kind of stuff. Another issue with the rear profile is its aerodynamic properties. Having it cut back into the bottom of the trailer is causing a low pressure area back there. This is working against you and causing some loss in gas mileage. Wouldn't the idea behind the design still work if just reversed it? You would still have the clearance and it would be much more aerodynamic.