This is the actual template from NFM. They charge you for it but when you return it they will credit back your $90.00.
Installing these ports without one is just being penny wise and pound foolish, so don't do it.
As you can see from the photo these templates are very heavily made and have built in drill guides which make drilling straight holes, through angled cabin sides, very easy. I have included a pen in the photo to show how robust these things are.
Please plan ahead when buying from NFM as they often run out of templates. I waited almost 5 months to get one and came very close to not buying NFM ports because of this!
Oh, and if you do use a template, please send it back when you're done so others don't have to wait eons to get one...