You’ve got several camp options between Diamond and Separation. The only desirable spot between Separation and the Grand Wash Cliffs is Surprise which you’ll likely have to share. Lot’s of folks prefer to night float starting at Separation. Surprise is a pretty side canyon, but you avoid the daytime helicopter flocks below Quartermaster at night.
As far as scouting, 232 mi, aka KFF deserves a look to convince yourself you don’t want to ride the wave train like this boat does: