Hey Swampyankee,
Give a little more detail on this former bump.Llikely it could be sanded down without causing problems.
What is the fuse made of and where exactly is the bump? what plane is it for?

IF it is a balsa sheeted fuse a couple of pieces of scrap balsa place INSIDE the fuse next to the proud spot would allow sanding the outer surface evenly without weakening the sheeting.