Can't believe nobody has asked, but were you planning on towing with your cockpit cover on or off? NASA air in your tires could really effect the harmonics of the air flowing past your trailer. Without nailing he leading edge of the cover down (lag bolts are optimal), and using NASA spec Velcro, you'll definitely risk damage to the top, your fiberglass, and endanger the lives of those around you.

Now are you running 5 or 6 bolt hubs? And what size wheels? What is your x dim.? With out all this info nobody can really calculate correctly what your outcome will be. If you have one of those Fountain trailers with the high X dim. I hope you are running the #6 bolt hubs or you are risking axel failure! And when you measure the axel grouping length don't include the front and rear steps, because you know Fountain has the long front step. We only need to know the running surface.