We camped there heavily from 2009 - 2013 but have not been back.
It is a more rustic type campground, and now with our larger 5er we just don't fit. We are lucky to live close enough for day trips to Hot Springs so that is what we mainly do now.
The little town is awesome, the spa is nice according to my wife, and its neat to sit on one of the spring fed hot tubs.
I can't speak to any of the road for dual sport bikes as it is not something we have done. If I had to guess there is some decent riding in the area, it's one of those places that just seems like it would have old fire tower roads, etc.
Here is a shot of some of the sites (from 2013). These sites were around 440 - 447 are that back up to the river. The pole has power on it (30 amp) and the water connections are actually in an enclosure on the ground. You will have to reach down about 2 feet to reach them.
This was our 33' 5er backed into one of the river sites, not a lot of room to spare length wise: