DIY Carboy Hauler idea

I, like many others am worried about the potential for injury (& lost wort!) of carrying around glass carboys. I have already taken the first step by carrying my carboys in milk crates, so I can get a better grip. However, I came up with the idea for this little carboy dolly to reduce the risk of dropped carboys.
Wondering if anyone has done something similar?

Materials:

(1) 16"x16"x.25" piece of plywood
(1) 5' of 2x2
(2) 1.5" Steel L brackets
(1) 48"x1" PVC pipe or dowel
(2) 2" swivel casters
(2) 2" rigid casters
(1) 2" bolt
a few wood screws

Basically mount the 2x2 to the top perimeter of your plywood. This should be the correct size to fit a milk crate snugly into. Attach the L brackets 1" apart on one side. Drill a hole through the pvc or dowel. Attach the dowel between the casters with the bolt, making a 4' pull handle. Mount casters to underside. I'm thinking that having the swivel casters on the same side as the pull handle would work best (like a Radio Flyer wagon).

I haven't had the chance to build one yet, but I did draw up a little pic in photoshop:

More of a "carboy wagon". Cool idea.

I was thinking of something similar, but am trying to figure out a way to have it jack up like a mini motorcycle lift. Nice and low for pulling around, but can jack up to at least counter height for racking.