I have used several procedures over the years. One is a variation of what you did: Lower the trailer tongue to the ground, put a support under the transom, jack the tongue as high as it will go, support the bow, and lower the tongue. This leaves the trailer under the boat. Although you can remove the board and have enough space to paint or wax the hull, you can't check the fully-extended CB position.
Another approach requires a couple of strong trees or reinforced rafters in your garage. Rig a block and tackle at bow and stern and hoist the whole boat straight up. After I drag the trailer out, I put supports under the keel so the thing doesn't fall on me while I'm underneath.
If you have a large flat lawn, you can also drag the boat off the trailer onto the grass with the mast up. Then you pull the main halyard down to careen the boat on its side. I have also done this during the season in shallow water to clean the hull.
Check out the Daysailer.org forum. There are exhaustive discussions, procedures, diagrams, photos, etc. on everything to do with each of the many variations of this particular boat: O'Day Versions 1/2/3, Sunfish/Laser, Precision, Cape Cod, and more.