I do the same with my kids 3 and 6. I also use an inflatable with windsurf attachment and super light kids rig. They can't hurt themselves when they fall on the board and is super stable. Works really well. You just have to watch the movie "Children of the Wind" to see how early kids can windsurf well.
^ I used to own one but in the photos above it looks inflatable. And the title is 'JP Air Funster'. Inflatable would fit in the car leaving room on the roof for my gear on holiday trips : )
edit: duh EP - click the buttons on the page. I see now.
