I'm also a big Trailex fan. I'm having my 4.3 trailer converted to double stack right now. It'll end up similar to Dave Fort's double stack which is pictured on their website.

While I was at Trailex they showed me their A cat trailer. It's set up from the factory to hold the A cat from the beams rather than the hulls.

The really cool thing about trailex trailers is the custom extrusions with t-bolts that they use. It makes the trailer infinitely adjustable without drilling holes, welding, etc..