First up, best dressed
Last time I floated Ruby/Horsethief and signed up for a campsite the previous evening, we got screwed by a big party who camped in our space. Which I gather is pretty common practice.
We did it over a weekendó too crowded. Weekday would be the ticket. Sign up the evening before and put in early. Or, do two camps, with Blackrock the second day. You'd beat the geeks down there, and could spend the afternoon hiking or swimming.
There are some neat-looking canyon hikes on that reach.