NGC- Renovating Airstream Caravan advice needed

[dibble]

Hi Friend of mine is converting an Airstream into a shop for his brother.

He is trying to remove the plastic interior coating so he can buff the inner skin to match the outside.

The beige plastic stuff is resisting everything short of extreme violence.

A hot air gun has removed a bit leaving some hard glue, this can just about be removed with Cellulose thinners.

Anyone know another way?

Cheers
Dibble