My husband and I built up a 5x8 trailer this summer. It doesn't have the metal side rails or the attached ramp, though. We wanted to transport 4 kayaks, fishing and camping gear, and 4 mountain bikes. We laid 2x4's around the perimeter, laid plywood across the top, and added locks, latches, and hinges so we could open the top. Just that bottom part fits all of the paddles, life jackets, fishing poles, bike locks, etc. Then we added superstrut to the sides and top for the kayaks, modeled after the Malone kayak rack http://www.amazon.com/Malone-Racks-U...oss+Bar+System

We also added some water noodles to give it that homemade look and to protect the kayaks. We used the Thule kayak carrier and tie downs we already had, and bought locking fork mounts for the bikes. I really wanted the gutter style bike racks but they were too expensive and we couldn't find anything suitable to make them with, and the fork mounts take up less room. We also cut some plywood to make sides just so things wouldn't rattle around. I'm thinking about adding a locking storage box or one of those truck bed boxes to the front, but I'm not even sure we need it.

I will have to ask my husband if he took any pics while we were camping. We just took it apart to fold it back up and store it yesterday.