I have a 4 tray, built in, tackle storage box on my boat and was going to store my soft plastics in these 4 trays. Now I'm thinking that this Texas summer heat may be too much for the plastics to stay stored on the boat when not in use? Do you think the heat will "melt" or soften these plastics to a point that they cannot be used?

I've got some that have been stored in the bed of my truck for a number of years. It has a tonneau cover so not exposed to sunlight or rain, but most definitely extreme heat. I have not seen any degrading on the worms. About the worst I have seen is some of the plastic bags will sort of melt and become brittle, but doesn't affect the plastic worm that I can tell.