Thought about this driving back last night after brief discussions during the ride.
Could propose two seperate routes here - one involving overnight bothy stay as shown on map (see Page 1), for which numbers should be limited , plus another route of shorther duration for completion on the Saturday.
The two obvious day routes are:
1) Bridge of Orchy to Kingshouse and back (approx 25 miles XC on landrover track/WHW) - not a bad run in itself with good postcard scenery and the necessary beer station
Plan would be for whole pack to depart BofO together, quick lunch at Kingshouse, then split into trwo groups for bothy/return to BofO
Shown on map as points 1 - 3.
2) BofO over forestry track (sometimes rough with potentially difficult river crossing, dependent on rain) to glen Orchy, returning to BofO via tarmac singletrack road (quiet)
In this way, a big turnout (like Dunkeld) could still occur but with lesser numbers staying for the bothy night.
Of the two options I'd say no1 is better/slightly easier terrain. Both routes are approx 25miles as return trips.
Sound like a plan?
Photos below are on the Option 1 route