addison, I also built a Mill Creek,the kids and I have enjoyed it immensely me for paddling,them as a platform for swimming under and jumping over. I think a kid trying to paddle a MC13 would be like you or I paddling a 4ftX18 ft dory.

I built a pygmy a few years ago and think it is an excellent boat for the 90 to 130 lb person. but for some one smaller it is still wide. my 80lb daughter just learned how to roll a fiberglass Poquito which is around 19"wide. I think the biggest problem in getting a "kayak" for a kid is that few children enjoy a fixed body position for long.

So my two cents for the big bucks option is a pygmy 13 or 10, for the low cost option would you consider a dory like kayak made out of one sheet of plywood? I made one for my nephew that was too narrow but the general idea is to make a dory/pirough/canoe out of 3 panels,close off the ends of the boat for huge flotation and small open cockpit, make a shallow skeg at the stern as it will spin almost like a river boat with too much rocker.

A kid can spill out of it,drag it around, and you will have spent about one week and $15o of high cost materials to make it.