[mickmate]

Some thoughts from me.
With the low center of gravity on these things you'd be hard pressed to roll it over, especially on the street.
I don't think you should have a rollbar unless you're wearing a helmet to protect yourself from it.
I don't let passengers wear shoulder harnesses if they don't have a rollbar as it holds you up in harms way.
It's your car and your kid, you can decide what's best for all of you.
It is a great family interest/hobby but nobody wants to be hurt by it.
I think when, where, and most importantly how you drive it are the considerations.