i think you might be thinking of Secret Pass Canyon, never heard of a secret lake but after rains or snows there is streams running down the mountains. its easy to find just go south next to Laughlin Ranch on the parkway just north of silver creek and there will be a turn off where you can park...
yes your green sticker will be okay, i would like to meet up but my teryx will be in pieces this saturday putting in some race seats and exhaust but thanks for the invite.
i live out here in Fort Mohave and there is alot of trails off silver creek, most of them are now marked with BLM markers, also check out Moss Mine off silver creek. You can also take powerline road all the way North to Hwy 68 and there are so awesome trails over there to. But Oatman is good...