You really don't have to get too fancy with this if you don't mind what your mechanic might say. Just work some correctly sized fabric through the spring coils wrap it around the boot a few times an zip tie it in place. That should last until the strut wears out and would be alot less work.

The water, salt, sand, mud, dust, etc. will ruin the struts in short order. Crud will build up on the piston shaft that sticks up from the strut cartridge and then will grind against the strut seal every time the car bounces up and down. You will soon have no seal left, fluid will get out somehow, crud, mud and water will get in, and you will have to replace the strut insert anyway. Much sooner than you would have if the boot was intact.

You can get away without replacing the boot if your struts are bad enough that you are going to replace the inserts within about 3 months. But, if the inserts are likely to live much longer than that, I'd say replace the boots now. It is not that bad. Not my idea of fun, but not really that bad.
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1955 Human, Scott; 1991 745 Turbo, Brunhilde; 1990 745GL, Snuggle Bunny