Update: Have now been tooling around with the Croozer for a couple of weeks and I LOVE IT. I put a little piece of carpet inside to stop loose items rolling and rattling, and I've been hauling things all over the place. Had one rainstorm, and the cover did a pretty good job keeping most of the rain and mud out.
My friends have gone from thinking I am nuts to being pretty impressed with the whole idea.
Oops, I wanted to add a picture but I accidentally deleted it... must go find the camera again.