i've been in the same boat this spring, with gas $4 a gallon I cant afford to be wasting gas doing a bunch of after work runs around town.
our local ace hardware has some lawn and garden trailers that ive been eyeballing lately for this purpose. basically its like a kids wagon but a little bigger and beefier, with big ole rubber wheels. they have three varieties that i think would suit boaters well. the first one
has some walls so you can have a compartment to store all your shit, and then you just cam the boat to the top to close it off. the second one
is just flat and the third one
is high grade plastic, but also more expensive, and it has a longer wheelbase and shorter walls.
the one drawback that you would expect looking at it is weight, but honestly its not too bad. i went to roll one expecting it to be a big bulky hunk of metal, but it is surprisingly light and mobile, especially the plastic one, which was very light.
my pops and i are way buddy buddy with ace so I intend to take my bike down there this weekend and rig up something for a test ride, but i think im leaning towards one of those more than anything.