That’s what flashes are for!!!
Here’s the setup:
SB-28 on a boom held by Duane, gridded and gelled with 1/2 CTO, shining down on the climbers when it was aimed right (not easy as the beam is small)
SB-800 on a tripod with beauty dish and 1/4 CTO shooting at the back of the climbers towards the boulder
Ken is lit with a combo of natural and flash light in these shots:
