Patrick, doesn't your trailer have room for both kid and groceries?

After my kids grew too big to ride in the trailer, I gave it away. It wasn't long before I regretted this, so I bought another. I've towed over 100 pounds with it. It's really amazing how easy it is to pull so much weight, and I even live in a hilly area. I just shift down a gear or two, and it's hard to notice the difference until I notice my moving speed. Also, a trailer has no effect on the bike's handling. I have even hitched the trailer to my racing bike and gone around turns at high speeds.

I have even gone to Costco and bought a Costco-sized load, the kind that would fill the trunk of a car. And I towed it with an old heavy three-speed bike!

Backing the bike up is one of the trickiest things. It's the same problem that tractor-trailer drivers have, since you now have an articulated vehicle, so to speak.

Check out the Utility Cycling section of bikeforums. There are people towing much more than I tow. There are also very inventive trailers there.