If you don''t want to drill more holes in the deck, you could weld a ss pipe to cars on the existing track, and go from there. You could experiment by lashing (firmly!) the pipe to the cars, and using blocks and lines
you already have on hand. A few feet of SS pipe should cost less than $25.00, don''t you think? A galvanized ring for experimenting shouldn''t be more than $4, though a ss one might be pricey. Rigging
it this way would spread the load of the jib
over two cars, instead of the sole one in the current setup, but would put quite a load on the welds. Seems worth trying if you''re unhappy with the way it is now.