David
For your runners i would suggest a tackle hooked to a chain-plate with the fall leading from the uppermost block down to a block on the deck which gives you a fair lead to the sheet winch.
I regularly race a 36' gaff cutter which has this arrangement, the tackles we use are 4:1 and it works very well, although for your boat a less powerful tackle might be more appropriate.
The backstays attach to the chainplates with simple hooks, so when running downwind it's easy to unhook the stay and move it forward clearing the boom and mainsail.
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