Maybe this will help someone to not over-engineer a kart: in Vietnam you can rent karts bolted onto hoverboards. They have pedals for forward/backward that just tilt the hoverboard in the right direction. Very low-cost solution. Steering is normal with the front wheels.

You can get these in the UK as well based on the squeals of joy I heard from two lads racing up and down our road a few days back - looked like great fun!