My quick estimate would be:
Pre-covid ride capacity (assuming it’s running perfectly with no stoppage) = 1500/hr or so
Current ride capacity (with 1 party for ride vehicle) = 750/hr ??
750 x 9 hrs = 6,750/day
I’ve seen HS capacity listed as 60,000 (which may or may not be accurate).
25% is 15,000, which might be a typical crowd right now since many days are selling out the park reservations. Maybe 2,000 or so of that are not trying for a BG.
So 6,750/13,000 = ~52% chance of BG, all other things equal. (A lot of assumptions in that number though.) Others may have a better estimate.
I think the best strategy with 10 is for multiple people trying for the entire group with MDE’s linked. Improve the odds equally for everyone to get one, otherwise there’s the chance of some getting one but not others.
ETA: Also, trying separately has the risk of everyone getting one, but at vastly different times, really throwing a wrench into your touring plan.