A few years is too long. I doubt store bought grape juice will benefit greatly from either cask aging or bottle conditioning. Wine is easy to make just hard to make not taste terrible. Keeping all your equipment clean is a lot of flavor battle though which is difficult in this beach-pruno scenario I’m imagining.
You live in a van on the beach, just bulk buy grape juice and leave it outside for a few years.
A few years is too long. I doubt store bought grape juice will benefit greatly from either cask aging or bottle conditioning. Wine is easy to make just hard to make not taste terrible. Keeping all your equipment clean is a lot of flavor battle though which is difficult in this beach-pruno scenario I’m imagining.