Hi. You're right, it's usually the 2nd weekend in July....not sure of this years date though. The whole event is somewhat in doubt due to the local government clamping down on motorised vehicles using the majority of the dirt roads out there.
In Autumn last year the Col du Somellier underwent a process of widening and flattening, apparently making it now not entirely challenging. Many of the hairpins were effectively removed and it's seemingly now possible to drive a car most of the way up.
They've also raised a barrier well below the summit after which there's no access for vehicles permitted at all. In the early stages, motorised vehicles were only permitted on the route between monday and thursday, though I'm not sure if this still stands.
ALL THAT ASIDE....it's still a fantastic and amazingly scenic ride, it's just not perhaps the personal challenge that it once was. However, I'd still go back and do it again anyday.
You can camp at "Base Camp" about 1/3 of the way up the mountain, though you need to take everything up there that you're going to need. There are no facilities at all (sparing a lovely waterfall/shower!) and it's a looong bumpy ride back down to Bardo if you run out of
There is (or was at least) free camping available in Bardo itself, but again no facilities. You do get use of the municipal sports centre though for toilets and showers. Or you've got Bokki camping. This to be honest was a bit crap. Bikers are put in a separate field and it's a fair trek to the loos/showers/bar...it's also expensive and a good 3 or 4 mile hike back into town.
For me, I'd stay at the free camping in town.