BCPilot
You are correct in so far as that sideslipping a 172 with full flaps is safe...........but in the POH of some of the later models (dont know about the R and SP) sideslipping is not allowed.
Have been told that has to do with the elevator buffet.
FD
PS: Where is the top rudder on your aircraft? I have only ever found one on most aircraft and it is usuall on the thin end at the back
