It's funny, but since I don't want to mess with the trailer I was thinking the exact opposite. I sketched out increasing the radius of the curves on the bottom corners from 15" to 24" and bringing the 1x6 support beam spacing down from 9' to 8' so I could just leave the HF trailer exactly as sold including the stock spring and axle placement and height except for removing one crossbeam to allow for the dropped footwell. I actually made all the corners the same radius, which is less elegant but easier to build and I thought would provide a little more spacious feeling inside.

I would do everything possible to reduce weight on the trailer...something like okoume marine plywood for the body, which is strong but light, and white pine or spruce for the support struts and beams. The floors could be done in two layers of 1/4" plywood with much of the bottom layer cut away by lightening holes. I have also considered covering the "roof" (the whole perimeter except the floor, meaning the purple line in my sketch) entirely or partly in aluminum, acrylic sheet, glued/shrunk/painted dacron (like an airplane) or even heavy duty white polytarp in order to eliminate the plywood at the curves altogether except for the bottom front corner. There would still be plywood at the flats to hold it all together and provide rigidity.
In my case my wife has a big old Ford Explorer with a V-8 that can tow just about anything but my car is a Jeep Patriot rated for 1,000 lb (2,000 lb with transmission oil cooler and trailer brakes, which I'd rather not mess with) so I was hoping to get the weight down closer to 1,000 lb so I could tow it with my little Jeep.
Cheers,
Matthew
*******
Matthew Long, Editor
cluttonfred.infoA site for builders, owners and fans of Eric Clutton's FRED and other safe, simple, affordable homebuilt aircraft
« Voici ce que j'ai fait...vous pouvez en faire autant! » "This is what I have done...you can do the same!"
--Henri Mignet (1893-1965)