There’s no real issue with C172 and skydiving.
AP setup:
Set altitude to 10000 feet AGL.
Set speed to Vy. Once airborne activate AP HDG and FLC mode
Lean mixture as you climb to keep rpm at peak.
If there a thermals around, use it. If no thermals, then fly straight whenever possible to max climb rate
Ideally you get to the first marker just in time when reaching 10000feet AGL.
I set Flaps 10 when reducing speed for dropping to get it more stable
After the skydivers are gone. Reduce throttle to idle, set flaps 0. Turn to one side while applying full rudder in opposite direction. Now you either slip down to the ground (do not spin) or neutral rudder and acclerate to Vne.
Plan your decent flight path so that you don’t need throttle at least until short final. E.g. approach the final marker with Vne just above the ground. Carefully pull back to gain height (take care of the Gs) and reduce speed. Now you can set full flaps and land smooth on runway. 
