Many years ago, on my Catalina 27, with hinged mast step, I used two 12-15ft poles as an A-frame. On the cabin top two permanent mounts were installed that allowed the pole's flat ends to be pinned between its sides. The pole top ends were also flat and angled to form the 'A'. A bolt/nut were used to hold them together. Both the back-stay and the main-sheet were connected to the top of the A-frame. When the mast was down the poles were close to vertical. Pulling on the main-sheet caused the A-frame to pivot and raise the mast.
There were a few people who did the same thing with Catalina 30s.... Our boats were on lakes and there were no hoists of any kind.