First realise that I’ve not seen any board with a remote kill switch, so letting someone ride one of these is akin to letting them drive a car — they could go really, really, really, really far very quickly if they desired to.
Of course you could make one (or have one made) with a remote kill switch. I’d set it up with two remotes and the second remote just holds the wheel turned which allows the system to give throttle. If the board goes out of range of the first remote or if the wheel stops being held, then the system only allows braking and coasting. That’s how I would try it.
You could probably get a custom built skate for that, from someone on here.
Also, helmets are absolutely not optional.