I plan to replace my aged topping lift line with one I can lead back to the cockpit. The filament is frayed and needs replacing also. The manual says you can substitute mono fishing line if you don't want to buy from Doyle. What have you all used? Is there a good source for the filament? Any input on the size of the topping line? I don't find it in the manual and I'm not good at guessing. I just want the clamps for the filament to still grab well. My topping lift adjusts and cleats at the mast, not the boom. Thanks!