Yes people do FI ratings for that reason, but you are looking at a lot more flying and ground school for that over an Advanced PPL - plus the FI course does not necessarily teach you the same in the terms of handling skills, in fact I would say the APPL is a good thing to do
before a FI course!
I am of course biased, but hopefully you will get someone on that has done one, feedback on the course has always been that it is well worth it.
