Any ideas on how to plug a hole in an old fiberglass shower unit?

I took off some on cold north side and find bats all the way down to the bottom of main floor walls ,,,nestled in the pink fiberglass put in on renovation maybe 20 years ago.

We primarily do showers entirely fiberglass with nice doors.

I would guess the tub was installed 10-15 years ago and is likely fiberglass.

But I also know that most consumers out there don't care if there is 1" closed cell spray foam on their walls and that we used fiberglass composite windows vs vinyl windows and the list could go on, but these are things that I care about.

One other thing I am considering is install heat tape onto either the current PVC pipes or the future PEX pipes and then wrapping it in fiberglass pipe insulation.Does anyone have any recommendations in this situation. 

We have a 100 y/o single family buy&hold in Missouri and would like to turn the attic into usable space. ideally we could keep the rafters exposed in keeping with the character of the home, so the standard 6 inch fiberglass would not work. 

We have a 100 y/o single family buy&hold in Missouri and would like to turn the attic into usable space. ideally we could keep the rafters exposed in keeping with the character of the home, so the standard 6 inch fiberglass would not work.Is there a DIY compact type of insulation that would work? 

If you are looking to keep the property for 30+ years it will pay to step it up to fiber glass over the long run.

Same for shower if we do fiberglass base.