We have camped in Sinks Canyon twice in our 24ft Class C. Check with Google Earth and you will see that there are three campgrounds within a mile or so along the river. We stayed at the Popo Agie Campground, which is the first one you come to. Not a lot of sites large enough or level enough but we got lucky both times. We didn't check out the other two campgrounds. Google earth also shows boondocking sites further in near and beyond Frye lake.
There are some hikes from the campground and the Sinks and Rise are interesting to see. For something different you could make a 1/2 day trip to
South Pass City a couple of miles off route 28. They have tours and some hikes.
