This is almost completely incorrect. Until last weekend our tracks have been so dry and hard that no pushbike could ever damage them. Given, when the tracks get wet you always have the pushbike problem, however it usually takes some small amount of work to correct. The 1/8th cars however are a different kettle of fish. They are heavier and are putting down far more power than any of our cars and on our hard dry tracks it just tears holes. Castle Hill and St Ives developed holes big enough to lose a 1/10th car in.

I don't have any problem with 1/8th or any other scale of RC car, what I do have a problem with is peoples lack of respect for others property. Right, we may not own the land but we do maintain it and spend money on making a half decent racing surface.

Your comment about hassling a legitimate 1/8th buggy club I would have found valid, until they started deleting a polite post requesting their help. The only reason I posted on their website was because someone suggested that their members may be able to help the situation by educating people around their track or putting some mild peer pressure on these guys not to run at our tracks.
However, after getting comments on their forum that show they are using our tracks and having them delete my posts twice, and ban 2 different usernames and my IP address from their forum, I would suggest that it is the members, and probably even senior ones at that (ie moderator of their site) that are causing the issues.

We recently spent a bit of time smoothing out our surface and building a few more jumps. The jumps lasted 3 days while they were still wet without any pushbikes etc. We had one race day on them, then a group of 1/8th guys began running on our track and basically destroyed the third triple. Don't try and tell me that they are being reasonable or that they aren't causing damage.