You can, sometimes, run a line
under the boat from side to side and work from the bow back to lift it up (cradle the board).
A 3 inch strap works better than a line
(wider to grip the board).
I've done this with the 500 pound board on a Hunter 216, a 70 pound board should be a piece of cake.
Once the board is up, put a line
on it so it won't drop when you launch. Then wait til spring.