Since it was a specialized valve inside the toilet leaking, I simply turned off the water to the toilet & planed on buying the part when we got home. For the rest of the trip, we flushed using a jug of water. One trip lead to several more before I remembered to think about replacing the valve when the trailer was parked at home between trips. However, we & the kids have adapted well & the 4 of us can go over a week on a 30 gallon black tank. Since this is working so well (cheap), replacing the valve is a very low priority.
Alum can work for the tank, so can stainless, carbon steel, fiberglass, plastic, etc. . . . It all depends on your needs & abilities as to what will work best for your particular circumstances.