You may want to wait on the trailer for a bit to see if you actually need one. I'd love to have one, but I can't figure out what I'd use it for or where I'd keep it.
A special big shopping trip once a week or twice a month or whatever is more of a habit enabled by the load capacity of cars than anything else. I stop on the way home, use the handbasket instead of a cart and can zip in and out in 5-10 minutes, tops. I can't imagine doing the hour-long cart-filling sort of trip any more. Big waste of time, IMHO.
Trailers increase your cost, take up valuable space in a small apartment, and require their own repairs and maintenance. I'm not anti-trailer by any means--as I said, I'd love to have one. I'm just saying it's worth examining the assumption that since you're giving up a trunk you have to replace it with something. It can be replaced by methodology too.