The bottom cam can be removed near the tack pulley. 2nd & 3rd can be accessed through the boom cut-out. And the remaining two our a bit of a night mare, but do-able. The Nitros were designed around the old Fibrespar masts, at around boom hight, these were slightly narrower than the NP's. It does sound like sanding the cams will do the trick
It is possible to pop the cams on, but it will be difficult with the NP mast and the narrow luff tube.

Cheers