ljs: Heating silicone caulk with the high setting on a hair dryer will work, the only problem is that you have to find some way of actually removing without scratching. Heating the caulk seems to make it pull off easier. How about trying a (don't laugh) plastic spatula (used for cooking in teflon pans). This should not scratch the fiberglass. Worth a try.

Heating it will help some. To get the residue off, try using acetone. then polish the tub using Sho Car Glaze car wax or 3M Finesse It. It's available from autobody suppliers.

Patty B: I didn't laugh !!I'll try it
Stephie D: I build hot rod cars when time and money permit, and know of this wax !
Thanks for the tips, they both are worth a try.