Bob
I have owned 2 Sport lockers. They worked but they are not durable, they leak and they have poor ventilation. I reccomend having an aluminum box made. Make sure the lid has a lip and is strong enough to stand on.
If you need a design I can send you pictures of the one Doug Graf made. It is the best thing I have ever seen. I keep my sails in it because it is drier than my garage.
If you want a sail tube, I have some 10" ID high pressure fiberglass pipe. It's heavy probably ~100 lbs
Carl