There has been much evolution of mast raising systems.  One of the latest is illustrated here.  It uses a simple A frame built from 2X4s or electrical conduit.  The A frame has a sheave or block at the apex and a small trailer winch bolted to one leg.  It stands on the deck inside the mid ship stanchions and is simply lashed in place.  As it is non rotating, it uses a fixed line to the stem fitting to hold its position and a bungee or line from one of the legs aft serves the remaining support.  A line from the small winch routes to the apex sheave and then to a stirrup that wraps and is hauled up the mast to just under the lower stays by the mainsail halyard. 

This A frame is a non rotating design which makes its length non critical and easier to construct and position than a rotating design.  The legs fold together at rest for easy storage. If it were needed for river travel, it could be built using collapsing tubes and made quite compact.

The above system works very well for the single hander because it places them in a position to handle the roller furler at same time as cranking the winch.  An optional method would lead the hoisting line from a turning block at the apex of A frame through a jib car and aft to a sheet winch with the advantage of saving the cost of a trailer winch.

A two height simple mast crutch can also be built from 2X4 and plywood scraps.