Tom does have at least one boat designed for kids, forget what the name is but it's on his web site.

Btw, I've roof topped and taken on my trailer many thousands of miles with my Yost boats with no problems at all. A cockpit cover is always a good idea if it rains, they can hold a heck of a lot of water filled up and fill amazingly quickly sitting on the car's roof. I once had to bail a poly boat with a coffee cup in the parking lot at work while the boat was on the roof, filled right up to the coaming in a thunderstorm while I was working. ( a coffee cup is a very slow way to bail a kayak btw)

The idea of a bow and stern line is an excellent suggestion.

Bill H.