What I mean is, just bring the one that you currently have on the go. I shall be bringing mine, even if only to get people's advice on how to progress it, though I hope it will be driveable by then.
I am sure whatever you have will be able to drive, even if it isn't finished. I have seen video of unfinished karts on the track. It encourages people to be able to see projects in progress and I think that, given your experience and advice to others, people would like to see what you have done on your own, particularly as it will likely be the distillation of all the best of what you have learned.