The thing about a p-hull in a model is that it's hard to fit because the hull is quite thick and the model is made for the outside to look good, not inside. And of course, Ok, the TWO things about p-hull are the inside/scale thing, and that VERY little will be seen. Plus.., OK, the THREE, the THREE things...
Seriously, it is worth having on in there, but you don't need it perfect, little can be seen even if you paint it fluro yellow and shine a light. having SOMETHING is definitely good tho.