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How about two reverse bilge pumps??

Put everything into ZIplocs down below, to go under the bridge just fill the boat until you lose two feet of freeboard....

I'm voting for dropping the mast vs shortening the mast. The procedure is much less tipsy without a furler. Do away with the furler, you can always sell it later. Run your jib halyard to the cabin, tighten up your baby stays, now when you go out to the Ocean you don't even need your forestay pinned. Pass under the bridge with the mast back as far as necessary. Next winch the mast upright with the jib halyard tied to the forestay tang, then make the trip to attach the forestay and hank on the jib. You can go up through the hatch if the water is rough. You would need to go back and loosen the halyard in order to attach the sail head in order to raise the sail.
Coming back in to the bridge may be more difficult since now the forestay is pinned. Either way the weight of the furling system is gone and there will be less flop. Coming back I would just lower the rig to the crutch and secure.

Global warming may raise the seas higher than your shortened mast clearance

Hope you don't experience any 2 foot waves going through.
Skewering a bridge with your mast from underneath doesn't sound much more fun than banging your mast against it.
I use a Hardtle/M type raiser, it's easy to build, easy to use, (1 man), cheap, and doesn't hack the existing running rigging, (=resale value).

One thing about rigging the mast dropper over the cutting approach

If you had a prolonged period of higher tides you would end up dropping the mast anyway..

or else cutting more off the mast and buying a third set of sails

Don't know if you have a dodger/bimini, but maybe you could cut the bottom of the mast. Boom would be lower and this might reduce lean somewhat. You would not have to relocate any fittings at the top of the mast. Don't know if this would give you two feet, if it did, you wouldn't have to tweak the sails.

Thanks for more input.

I certainly don't want to get rid of my genoa roller furler. I like it too much.

2 foot waves under the bridge? I've watched it and studied it. It doesn't seem to happen. The water going under the bridge is dominated by the tidal current, which seems to be about 6 to 8 mph, or more, either direction, filling and draining the intracoastal, so the ocean waves don't seem to enter. The open ocean inlet is about 100 yards from the bridge. There are laminar (smooth) flow areas in that area, but the current is just way too strong to risk trying to stop and raise or lower the mast, especially with power boats going by. It's too easy to be smashed into the rocks and concrete seawall along the sides.

2 foot waves are easily generated by large power boats going through, but I just wait until their wakes die down under the bridge, and the passage is clear, before going through. Because of the fast tidal current, all the power boats zoom through. Lucky with the Mac, we have enough power to get through the current easily. A normal small sailboat with a small hp motor would get bashed around under there. Actually, a lot of large power boats without enough hp or with skippers not paying attention with the way the current accelerates through, have been seriously bashed there. This is the ONLY inlet to the intracoastal for 13 miles north and 13 miles south, so a LOT of tidal water pours through there.

The gooseneck is 28" on my boat, but that's not enough ... don't want the boom scraping across the slider, nor parting my hair~!

If I did cut the mast, cutting the top seems easiest. It's four feet from forestay to the top, so the backstay and the mainsail are the only changes. Ask your sailmaker, but I'd think it better to cut the main along the leech instead of the foot. It makes for a fatter aspect ratio, retain more canvas for your lighter air sailing, and also maintains the existing reef points.

Seems like a bad idea to me, but seems above is the lesser of evils. Good luck!

Since you are planning to keep the boat for a long time do not forget that ice caps on both North and South Pole are melting and see level is rising. In 10 years you might be hitting that bridge again.


Zoran

Could you heel the boat enuf to sufficiently reduce mast top height?
As by .....
1.with sails down, support aft boom end with topping lift, add weight (e.g.anchor, water bucket, brother-in-law, whatever) to aft boom end and swing boom out over the water (assumes strong enuf gooseneck);
2.add crew weight on lower rail;
3.empty water ballast
Just a passing thought....no calculations or trials done.
Good luck!

Assuming the step is 6 feet above water and mast is 28 feet long, I get

arccos (30/34) = 28 degrees of heel.

The trick would be how to heel the boat and hold reliably while you power under the bridge, I think.

You could add a periscope, flood the ballast and slide under the bridge