This is one of the more interesting posts I have seen in a while. First, it strikes me as strange that "fly guys" would do these types of things (not necessarily the verbal abuse, but the vandalism). Regardless, there is no reason for your property to be damaged. As a recent victim of a car break-in on the river, I still am carrying some rage around.
You are certainly entitled to your privacy regarding why you are allowed to have the permit in the first place, but it might be helpful for the board to get an idea of why you have it (I hope you aren't blind, considering you are packin' heat). It does seem a little strange to me that the WDFW issues these types of permits (probably best not to try to understand all WDFW decisions). It would seem that these permits are aimed at people with disabilities which would, by nature, make access to "fly only" rivers difficult. Also, based on Smalma's quoting of the regulations, it sounds like fishing is only allowed with a casting bubble (I think they are referring to the clear, water-fillable bobber). These casting bubbles are usually fished with flies beneath them (what IS the difference between a weighted fly and a jig?). It sounds to me like the idea of the permit is to allow disabled people to fish with flies in fly water if they are not physically able to cast a fly rod. I guess it makes more since to me to allow these permits for fly-only lakes but not rivers (if a person can access the upper Hoko, how disabled are they). Is the point to "even the playing field" by allowing disabled people to fish less competitive waters? I guess I don't really know where I am going with this, but the whole idea of this permit sounds a little odd to me.
As far as the VERBAL abuse you have suffered, you certainly don't deserve it but I see why it happens. For every person like you with a permit, there are 10 others that either don't know or don't care about the fly-only regs. It sounds like the upset fly guys would have been better off having a conversation with you (usually the best starting point on river etiquette issues) than just verbally unleashing on you (you know what they say happens when you ass-u-me?).
Gottagofish, do you have any idea of the number of these types of permits that the WDFW issues? Just curious.
Keep your spirits up... Karma has a way of working these things out and whoever destroyed your property will likely pay the price later (where are the attacking cougars when you need them?).