John,
Can you raise the mast from the front of the boat? If so, I've got a slick system than should work. It avoids the problem of holding up a nearly unsupported mast and having to rotate it 180 degrees; and, it can be done alone quite easily. The only drawback is that you can't do it with the boat on the trailer. Since I launch off my skinny beach wheels, I don't mind at all. Let me give you the quick version:

1. Take boat off trailer and position it next to the trailer with bows no further forward than the trailer wheels on beach wheels/foam supports
2. lay mast so top is resting in the front trailer support and bottom goes diagnally down to the mast step; pin in place
3. hook up one side stay (on side nearest trailer), forstay/bridles, and run the spin halyard; then, run your spinnaker sheet through the block on the side furthest from the trailer and tie it to the side stay to be connected on that side
4. grab or position the spin sheet where it will be easy to grab; working from the front, hoist the mast--you'll have to step over the bow as you raise it diagonally
5. once the mast is fully raised, it should be connected by the forstay/bridles and the sidestay nearest the trailer; at this point, pull the spinnaker sheet tight; that will tighten the unattached sidestay (or trap line could also be used)
6. hold the spin sheet taught and walk around the side of the boat and fasten the second sidestay
7. mast lowering is exactly reverse and very easy since the spin block--if run the right direction--is used to ease the mast down gently

Hopefully this doesn't sound more complicated than it really is. Paul K. and I both use this approach and it is very easy. In fact, whenever someone offers to help either of us we usually just say no thanks--just too easy to do solo. Safe, too as the mast is connected in 4 spots the whole time.