The pigtail on the spin clew works great but it still leaves the sheet on the tramp to flop around.

On my tramp, I have a grommet in the back (two actually, one for the halyard and one for the sheet) that has a bungee running through it connected to a block that the sheet runs through. It stretches the sheet out all the way to the back of the tramp so theres no slack to go overboard. The downside of this is that it sometimes gets knickered up with the halyard and mainsheet back there. Butt-cleats also get in the way sometimes.

The BEST solution I've seen is the one that I saw on the Keysailing boats where a bungee is run all the way out to the front of the spinpole, all the way to the rear beam (for plenty of stretch) and then the sheets are taken from the turning blocks on the front beam, and run out to the sides under the tramp and then sucked up via that bungee. The bungee allows you plenty of slack to sheet the spin but enough tension to keep the slack under the tramp and out of the water. I wish I had pictures of it because I want to reproduce the system on my boat.