Bike + bike trailer has great utility, especially after the BOV runs out of gas.

Here's one of my mountain bikes pulling a dog trailer (holding two puppies). That is a "Croozer" brand dog trailer rated to carry 100 pounds. There's also a luggage rack that fits on top of it and there's a third wheel and handlebars so it can function as a stroller.

There are a number of strictly cargo trailers to choose from. A child trailer would also hold a fair amount.

I'd enjoy a thread on non-motorized BOVs.