Mark,

I used Scotch #471 Plastic Tape.  It is available at Automotive Paint Stores
in 1/4, to 3/4" widths.  Just elastic enough to turn a radius and tough
enough to sand up to with say, 180 grit (I used two plies to be safe) .  I
don't know how long this can stay on Plexiglas and be easily removed without
residue.  Probably depends on temperature.

Steve Colwell    Legacy 15SC reserved----primering the belly