Bumpers

I need to get my bay bumpers cleaned up. I took the front one off the other day and noticed some rust starting to grow inside the front one. Whats the best way to prep these before spraying in 2 pak. I was thinking maybe getting them sandblasted as my sander won't fit in the inside of the bumper to blast all the surface rust out?
Anyone know of a sandblaster near the bribie/caboolture?
Is it worth loooking at powdercoating them, i've been told that powdercoating cracks easy specially if your doing up bolts on to it.

I used those Rapid Strip discs tee bare metal surfacehat are made for a drill. You can get them from Bunnings or Supercheap Auto etc. They get everything off and leave a relatively smooth yet rust free surface.

Cheers,

Skot