I had to do some repairs to scrapes on the runners on the bottom of the hull a while ago.
Needing to take the mast off the boat due to lack of space between a shed and the ditch to turn the boat over, I used a block and tackle (actually a fiddle block with double pulley, cleat and some extra turning pulleys) to give me the leverage I needed. Secured to a convenient tree. I ran a line from the cleat on the bow, through the grab handle at the spray rail and onto the traveller rail on the stern (making a bridle). (MKII boat) to spread the load rather than carrying all the load at a single point and attached the pulling line to the bridle.
As well as padding underneath the hull, you might also need to stop the hull sliding along the ground as you start to turn the boat over. I think I was able to just put my foot against the bottom initially and as the hull turned and the weight came on the bottom, it stopped sliding.
Having a cleat in the block and tackle system makes life much more convenient but you will need some way to tie off the lifting ropes anyway. If only for a breather if working on your own.
hope this is of some help