Heres mine...probaly bigger than what your looking at. I was planning on going they way of that trailer in your link...by the time I had it all built up, it was about the same price as a commertial toyhauler and had less comfort items. Mines a 21'. The only problem I see with ones like the one in your link, is its impossable to sleep in there with the bikes. No big deal if all you do is weekend trips to the track, but if you ever just needed to sleep in there on the way to someplace, your going to have to unload the bikes at a rest stop or campground or something. Then leave them outside. With a normal RV toyhauler, you can always use the rear bed, and if I have to, I can unhook one bike, roll it to the rear, and use one of the side beds.
Mike