Wish I had a link to show the photos of Hobie Gary's system "The Solo Right". He mad a "lever" (usually out of an oar) that had a small plastic "wafer" on the paddle end that would keep the end in the dagger board pocket. Then there were two lines, one that attached to each crossbar at the hull intersection. The lever/oar was made to angle up slightly out over the water by the length of each line. Then you took your regular righting line out with you as you stepped back out on the lever/oar. As the boat came up, you went hand over hand up the righting line and the boat righted.
He made the same type of system for my H21se out of a H16 boom with some non skid tape on it. It worked perfect. I was able to right that boat solo with that system.