OSHA is very particular on where you put holes into a forklift. Even if you are allowed to, they usually require written permission from the manufacturer. If you use one of these magnet mount kits, you can avoid the issue entirely. We used these magnets extensively to mount blue spotlights.
(1) 95lb pull magnet (3-3/16" diameter)
(1) Mounting ring (2-3/8" diameter)