I lost the storage where I had been storing and tinkering with my old Rans S-4 ultralight. I temporarily had it in a carport tent on my driveway, but with winter coming I needed a better solution. The dang squirrels were storing walnuts in it. Mission parameters for the build: big enough for my little plane, light enough to tow with my minivan, cheap (money for trailer comes out of plane budget), relatively weatherproof, life span at least a few years with easy repairs if needed. I broke this out of another thread (Shrink Wrap Wings), didn't want to interfere with that one. I started with a boat trailer. I found one that had 2 frame rails all the way to the front, was heavy duty (for stiffness more than weight capacity),and most important had the frame tops all in the same flat plane. Paid a whole $120 off a Craigslist ad. And it's even got decent tires and bearing buddies. If you want to build a trailer like this,I'd look for this type of trailer. It's an Evinrude Fathom Master from the 70s. They seem pretty common, usually found with a nasty old fiberglass trihull boat on them, which gets cut up and dumped.