Trackday Weight Limit
There are several trackday organisers, and a few companies out there, that offer track bike rental; but at a price. You would have to contact them directly at the time of booking to see if they have any weight restrictions for hiring their bikes. Or you could save yourself a bit of money and just use your own bike. Alternatively, book yourself onto a race school (Ron Haslam Race School, California Superbike School et al) and use one of their bikes for the day and learn a lot in the process.