Hello Alan,
I agree with Mark, you really need a topping lift. We have found that a masthead rigged topping lift is valuable for many things. Our topping lift is rigged using a masthead sheave so the topping lift runs from the end of the boom to the masthead and then down to a cleat on the mast near the main halyard winch. It can be used as a spare halyard, it supports the boom when the sail is down and we use it to scandalize the main when we are reefing.
Having lost a main halyard at sea we used our topping lift as a temporary halyard replacement till we got into port.
We use our topping lift to support the boom when loading and unloading heavy items like an outboard. We attach a 4:1 block and tackle to the end of the boom for lifting and use the topping lift to swing, raise and lower the boom much like a crane.
For reefing, pulling in first on the topping lift raises the boom scandalizing the main and makes it much easier to lower and reef the main. With the main halyard, reefing lines and topping lift all at the mast its a simple easy process to put in or take out a reef. Once the reefs are tied in we ease the topping lift back out and continue sailing.
Regarding the boom gallows, I understand what you're saying! I've smacked my head into our gallows many times over the decades. But I would not want to remove it. I've found it handy to lean against when I'm standing on the cockpit seats. I find that standing on the seats gives me better visibility when traveling thru heavy boat traffic, docking and when traversing crab pot and lobster fields. I did raise our boom gallows height by about 6 inches, but it still is a few inches lower than the boom when the mainsail is hoisted.
One other nice feature of the Boom Gallows is that it provides a handy post to hold on to when one needs to relieve oneself over the side.
Kevin