Can you keep watch while resting?
Group of 3 PCs, travelling in the morning and day.
In the evening Character A makes camp, Character B can rest (or try to roll survival and sleep), Character C keeps watch
In the night Character A and C sleep, character B keeps watch, forcing character B to be sleepy or sleep in the next morning (or having slept on a tree in the evening)
A makes camp, B rests and keeps watch at the same time. C can do something else