Charlie,
Check out my post, "Modifications to Trailex Trailer." I removed the bottom board from the keel trough and replaced it with rollers from Trailex (John H. is OK with the mod.). This allows me to inspect the keel and, if need be, roll the boat back and forward for further inspection/repair. If the bow stop and winch supports are moved forward a bit, you can roll the boat far enough forward to lower the centerboard. (You may need some help rolling the boat, and leave the winch attached to prevent rolling it too far back.)
I have liked the roller mod very much so far. I can make quick inspections any time, make repairs, and the keel drains water off instead of sitting on soggy carpet. The side boards stay in place to guide the keel.
Also, Jamestown Distributors has a couple of relatively inexpensive lifts at
http://www.jamestowndistributors.com/userportal/show_product.do?pid=98161 ($600) and
http://www.jamestowndistributors.com/userportal/show_product.do?pid=59042&familyName=JD+Boat+Lift+System ($900). The $600 model allows you to lift the boat about a foot above the trailer. Removing the bottom keel-trough board might allow you to drop the centerboard all the way, provided the trailer's cross-member does not get in the way. The $900 model stands on the ground and you can then pull the trailer out of the way after lifting the boat. I think getting all the weight you can (including ballast) out of the boat is a good idea if using these lifts. Safer, and less pressure on the hull at the lift points.
(I hope these ideas are helpful. Looks like we won't get a chance to sail this year unless an unusual warm spell comes. Otherwise, looking forward to spring.)
Dana