A few details of the mast lowering system I use.
My boat has a Z Spars mast and the heel is fixed with a single pin located towards the cockpit. I would prefer a tabernacle but get put off by the cost and complexity (because of the exit sheaves at the bottom of the mast) of changing it. So far I have used the present system for over ten years. I have to lower the mast to go down river under Rochester bridge on the Medway. I DO NOT have to lower it right down but only to an angle of between about 45 and 75 degrees from vertical (depending on the state of the tide). We are usually going for a few hours daysailing and the whole process is done whilst motoring along (I haven't found a way to keep sailing yet!). The system works just as well for unstepping the mast if required.
We have an "A" frame attached to stainless plates bolted to the toe rails, and from these plates there are two stainless supports which go to a slider on a track at the front of the mast (to provide lateral support to the mast when lowering or lifting). The forestay uses a Sea Sure qick release fitting instead of the standard bottlescrew, but it does mean I lose sail area from my roller furling gear. A multi part tackle is used from the "A" frame to the stemhead to lower or lift the mast. I find it difficult to describe the system using only words and don't think I can attach photos to this message board reply, but if anyone is interested enough to give me a ring on 01474 8853873 I will do all I can to help.
Royce Watchorn