I live 7 miles from home and keep a SHTF backpack in my car. I try to have something for all scenarios in it, which is causing me to buy bigger and bigger backpacks
I can appreciate that. When I was looking at a backpack for my trunk I put just about everything in it I could possibly think of. I'd much rather be in a position to take stuff out, than to need something and not have it. Currently, my backpack just has a new camelback water bladder and some meal replacement bars, but there's plenty of other stuff in the trunk that could be easily stuffed in the bag if it was needed.