I haven't camped on Patos, but my family used to vacation in the Juans and fished that Island back in the late 70's early 80's. The island is not very protected, so I'm guessing beaching your boat might be best. Back then, we worked real hard to get a few silvers, trolling aroudn the whole Island. We seemed to catch more fish on the East side of the Island, trolling back and forth on the south side. If you're targetting kings, I would troll the North side of Orcas in July from Parkers reef - east.

Having said that, if your looking for the best area to salmon fish / camp, try Garrison Bay, just outside of Roche Harbor. That whole west side of San Juan Island is good, with the best concentration of fish, I have found, by Eagle Pt. There are kings just outside of the harbor on the NE side of the Island as well.