Just my two cents for what it is worth, when you come up against a difficult area to fit a piece of panelling or sheet timber, use a section of cardboard and bit by bit trim it in until it is a perfect fit then transfer it to your sheet stock instead of trying to fit your sheet stock directly. It is lighter to move about and it doesn't matter if you stuff it up also not as expensive if you make a mistake, the key is patience, trim and fit and repeat as many times as it takes, it is amazing how perfect you can get it to fit.
