James - I'll give you an example. There are trails around the Crazy Mountains that have been used for more than 100 years. They are shown on current forest service maps. Nonetheless, landowners are claiming the public has given up any easements to them because the public hasn't been using them (something very difficult to prove either way). They have posted the trails. Some deny access altogether, others require you to sign in. The forest service claims they are public, but they don't have the budget to prevent the landowner from posting it or gathering written permission to use it or bring it to court. Access groups like PLWA don't have the resources to fight more than a couple battles at a time. So they remain unsettled. That actually seems to be the norm around here.
Compounding the problem is that with contested access the public are even less likely to use them. The trails become hard to find, which further bolsters the landowner's claim that it isn't being used by the public.
This is an interesting topic that I've just started learning about. Not enough people are doing much about it and perhaps I can find enough time to help correct the situation. This might be a case where the Forest Service needs to be sued to get them to do their job of clearly asserting the right of the public to use this trail.
"Use it or lose it" should not be a valid legal argument, but neither should "possession is 9/10ths of the law". The fact is, if you think you are on sound legal ground and want to do something, but fail to exercise your rights, then it doesn't really matter if the land owner has created enough evidence for some future date: The only thing that matters is that your rights were denied, today, by a bully. You can exercise your rights, or fight for the rights of future generations, or you can stand down and let the bully win.
I've heard about similar situations to yours, in Idaho and Utah, when it comes to roads in Wilderness. The public claims that the road was in use since long before Christ was a Corporal. I don't know how those situations pan out, but I'm sure statutes get involved, burdens of proof, etc. Here, in your case, you have the opposite situation. You've got the government on your side. If it's your right, use it or (maybe) lose it.
Here's what I would do. I'd go where I want, legally.
On the other had, I'm not a people person, but if I was, I'd get together with like-minded people and file the easement with the county recorder's office. Simple, cheap. Preserves the record of your claim and let's subsequent purchasers know there is a claim for easement on that land they are thinking about buying. If that can't be recorded or the recorder won't record it, then publish notice, to the public and to the land owner. This preserves your position against changes (over-grown, etc.). Make sure to state that your failure to exercise your rights to access is based upon actions of the land owner (physical threat). If he openly denies physical threat, then use the easement. Let him press charges and prove his case in court.
In the end though, if you have evidence of ancient use, then you are good to go. If you don't, then your predecessor's failure to do what you should be doing has burned you. And your children and their children.
But the answer is simple: If you have the right, use it.