If your boat has lifeline stanchions, you can attach small single sheaves to the base of each stanchion. That's what I did on mine. I have a larger single sheave attached to the bottom of my stern rail and I mounted a jam type horn cleat just aft of the sheave. I had to install a 4" Beckson deck plate inside my fuel compartment last week to gain access to that cleat as well as the stern cleat on that side. I think it's going to work out OK. I had a regular Herreshoff cleat mounted on the combing in front of my Gennie winch and that was a big mistake. The Gennie sheet kept getting caught on it almost every time I tacked. I removed it last year. I can post pictures of it for you tomorrow. I picked up the deck plate at a marine consignment store for $5 and the 4" jam cleat went for $2 at another consignment store. The sheaves, I've had for years and they're small single sheaves mfg by Schaeffer.
The sheave near the drum should be placed at a 90 degree angle of the drum so that the rope will wrap around the drum easy. I think my drum is supposed to have at least 22 wraps on it with the sail pulled all the way out. My furler is a CDI FF-2.
Joe