I swiped an idea from Hunter marine. I used two pieces of 3/4 plywood ripped down to 2 1/4" wide. I drilled a hole in one end on both pieces and ran a short length of rope through the holes, tied knots in the end so it doesn't slip through. I set the free ends of the plywood in the gap in the tramp at the back pylons, raise the mast and jam the rope against the mast to hold it up. This is good enough to hold it up until I get the front shroud line attached. Simple, and cheap.