Welcome.. to answer a couple of your questions. Radio dishes, would depend on where you were exactly. Larch has a couple doppler arrays on top. Most are weather some for communication. Yes the logging roads appear to travel everywhere up there. You must be aware that a lot of the secondary roads are being abandoned and not maintained. Also of note it is illegal to ride quads on any logging road, closed and gated or not. This is becomeing a big issue with national forest and dnr. So please do not ride on the roads. If you get caught on a m/otorized vehicle behind a closed gate the fine starts at a grand I bielieve. Just trying to keep you out of trouble.
Are there hidden mines up there? Hidden no. You just have to do some research to pinpoint them. Lots and lots of helpful info in this thread if you read through it. A couple to look for would be up silver creek, bluebird creek, and possibly prospectors. These are all way up high on the washougal. No vehicle access. You could possibly make it part way. Anyway hope I was of help.