You can try to make a claim, but I doubt you will have success.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.
City parks and camp grounds have different standards. I do not know if Thousand Trails is a private or public camp ground. That could effect the issue of liability. Why not make a claim on the comprehensive coverage of your auto policy?
It's a public company, Thousand Trails stock trades on the American Stock Exchange under the symbol: TRV. If your insurance won't cover, small claims court if amount is small.
You should get an expert arborist to look at the remnants of the tree that fell and any pictures. They should probably also go out and look at the other trees in the area. You should check with the city and or county where the property is located and see if they have any laws/regs re maintanence of trees on private property. If indeed there are many rotting trees presenting a public hazard, the local govt should be told so it can go out and inspect. best thing for you is if they do and cite the campgfround, etc hopefullly making your case about the poor maintenance.
In terms of general legal theory Thousand Trails has a duty to maintain the property and on its face it sounds as if they would be responsible for any losses sustained as a result of their failure. The other part of the analysis is that you have to carefully read the written contract you have with Thousand Trails. For all I know it may say that you assume responsibility for trimming the trees or removing the trees, take a look.
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