I built my mouse proof sail tube on my 21 trailer out of 14" round aluminum spiral tubing 30 years ago. Strong enough to lightly step on.
For my 16 trailer, I built a 10" long 1/8 aluminum "mail box" in 1986 that is mouse free. It is strong enough to dance on.
My three spare sets of sails are stored in a rack of three galvanized spiral pipe 12" round by 10' long, hung from my garage ceiling by unistrut and all thread rod. Never a problem.
Get with your local sheet metal contractor and be sure to buy the metal end caps too. Most companies have the galvanized pipe in stock and these work great out of the weather hanging from your garage ceiling. For your boat trailer, seek out aluminum spiral pipe with end caps from a larger more regional company.
Poynter Sheet Metal out of Greenwood, Indiana would be a good source for aluminum spiral with end caps. Buy in bulk with your buddies to be cost efficient............
Don't forget to use sail bags too. I purchased several from the Colorado Bag Company and they made my righting bags too.
Bill 404 21SE