Naaah. I’ve been in a Gator at 70. Go on the “buggiesgonewild” site and look at pictures. You’ll find something you can plausibly put a light bar on that will scare the crap out of the guys on the bike.
I think you’d better de-power your dirt bikes or introduce some bike-unfriendly obstacles.
It looks like 45HP is considered pretty high power for a dirt bike and can do 88 mph. I wouldn’t be surprised if it can do 0-60 in 5 or 10 seconds given the HP/weight ratios. And the bike is maneuverable and essentially all-terrain. So given your starting conditions (grassy field and a 5-10 second head start), by the time your security guards get on their vehicles, the guys on the bikes are already doing the maximum possible speed for the terrain and are already halfway across campus. There’s pretty much no way to close the gap.