3/4 mile is like a 10 minute walk. I'd probably just walk with some kind of a cart with my groceries at that distance, if you consider not having to lock the bike up when you get there and unlock it when you come out, having to hook up and unhook the trailer every trip, and if you have a push cart you can just go into the store with it, it would probably save you a lot of time to just walk with a cart than to use a bike and a trailer.

There are a lot of folding personal shopping carts on the market for pretty cheap.