Rich,
The club (SCCA) has classes for karts at solo events with a shifter class that runs at the Solo Nationals that ran in Topeka last week.
They had 20 kart racers from across the country this year. Like most motorsports the SCCA solo kart program has pockets of the country that are very active.
I know a number of the solo racers that run local kart club events to get in some wheel to wheel racing.