Maple Canyon w/o Reservation

Thinking about heading down to maple tomorrow night after work, but all campsites are reserved as usual for this time of year. My guidebook says there are a couple sites that you cannot reserve, and are taken at a first come-first serve basis.
Has anyone had any luck with these sites? How many non-reservation sites are there? Campsites outside the canyon?

Yes, there 6 sites (maybe 7) that don't take reservations, but the chance these are open on a Friday night is really low. There are sites along the road to the campground, donation requested if you use this option.
Other options:
there is camping on Nebo Loop utah.com/byways/nebo_loop.htm

Also Log Canyon which is north of Fountain green: utahoutdooractivities.com/m…

I've had great luck just doing day trips down from Salt Lake if that's where you're coming from. The roadside sites in Maple kind of suck IMO, but I've heard good things about Log Canyon (never been myself)