I'd look at the trailers that 505 (that's a racing dingy) sailors use. They are made by a French company called Rapide. The have several great features that would work well for kayaks.

1. Soft spring rates. You don't want to pound your beautiful yak to death with too-stiff springs.

2. Removable dollies. Basically the road trailer that hooks to the car hitch is simply a vehicle on which to mount an ultra-light dolly that is used to wheel the boat, by hand, to it's final destination. Picture this; the dolly (3-point) cradles the kayak (and the kayak is securd only to the doly) and the dolly is wheeled onto the trailer and secured with a couple pins.

3.Stacking options. As Jason mentioned. This would allow 4-6 kayaks (2 wide per level on dollies) depending on the number of levels provided.

Good luck w/ your a-levels.

Porter