Uni-bits are safe for Fiberglass, Composites, Plastics and and can't be beat for Plexiglas. No blowout, chipping or crazing.
The only real drawback can be the thickness of the material. In your case though a #3 Bit PN 10233 (max dia is 3/4") should do a great job.
Also Uni-bits can be laterally "walked" if you see you off a bit on center line.
https://www.irwin.com/uploads/produc...etal_eBook.pdf
https://www.irwin.com/tools/drill-bi...tep-drill-sets
If you do decide to use a hole saw. Once the pilot tip is thru run the drill in reverse while you cut thru the Gel-coat to help eliminate chipping. Then switch back to normal R/H drilling rotation. As others have said, its good idea to go to backside and score the hole with the the bit to prevent a lot of final hole blowout chipping.