The putty is mildly sticky, if you plan to thru drill the hole, then I'd put something on the other side of the hole. That plastic you mentioned. The best thing would to be get someone on the other side to hold it in place. But maybe you could tape it up. Coat the plastic with a thin coat of oil or maybe put a piece of saran wrap between the plastic and the hole. You don't want the plastic to stick, on the inside, anyway on the outside sticking would be fine. Thinking about it you could just put something heavy on the outside to hold the plastic down while you apply the putty. Tho a foot would be better.
On the inside you may want to get the putty as smooth as possible, a wet finger works OK for that and after a could days apply a little paint to blend it in with the ceiling. On the outside do what you were talking about plastic then eternabond.