A couple of comments...
On your rod holders, add small light bulbs to give it a headlight appearence and keep the rods dry...lol. Taillights are also going to be needed!
A two wheel dolly with the bottom extended works just as good, but not nearly as COOL.
Split one of the extra wheels you have, and use half as a hanger for the cords. Takes up less room on the cart, less weight, etc. (split in half at a horizontal plane, giving a half moon appearance). Allow the leads to hang, rather than wrapping them tight, as it is better for the leads in the long term (many years). Plus there is something about generating a field when you wrap a wire in a coil, but that is another discussion.
When pricing extra leads for the positive/grounds, consider putting 50 feet on the stinger end and 25 foot on the ground. That is what I use, and it seems to work out well and keeps me from having to rush to put everything up in case of an unexpected shower. If the ground doesn't reach, just grab a piece of angle iron (or whatever is handy) and tack it to the work piece, to bridge the distance back to the welder ground lead. Won't work well for the positive (stinger) end but it shouldn't matter on the ground.
David from jax (currently in Hagerstown, Md)