Maine has right to roam, kind of, in a very american way: you can assume you have permission, unless clearly indicated otherwise. This preserves property rights, but only if you want them. Also there is a strong presumption of zero liability for the landowner (AFAIK!), so landowners aren't particularly incentivized to close off their land.
Yea, I think the liability thing is key, at least in the USA. I have no problem in concept with allowing the public to roam on my property (as long as they're not taking or damaging things), but I wouldn't want to allow it if they could sue me and win because they tripped on a rock or something.
Anyone can sue anyone for anything. I assume that if you trip on a rock or a tree root on a trail on someone's land, suing would be a man bites dog thing--but so could any number of events. Obviously if you deliberately put some hazard of a trail crossing your property, that could be different. (Though probably edge cases--tricky natural hazard on a well-established trail you didn't do anything about.)
Do you know more about the tax incentives in New Hampshire? I'm in Vermont, and wondering if there are established patterns that would work for our town.
Edit: I'd love to hear from anyone elsewhere that offers such incentives as to how they are structured.
All thanks to the hunting lobby, I expect.