That will likely depend most on how you set up your fence(s). The OFCCP has long been on guard for contractors potentially gerrymandering their recruiting areas by, for example, choosing to pull availability data for select counties based on demographics rather than an entire (already defined) metropolitan area, and conveniently not including counties with higher proportions of women and/or people of color. So, for example, if recruiting recent or soon-to-be college graduates in the Washington DC area, the agency would likely have questions if you set up geofences on the campuses of Georgetown, American, and George Washington Universities, but not Howard (which is an HBCU). You should be able to monitor your geofencing to some extent by keeping an eye on your applicant flows. If you see a spike or falloff in applications for particular groups based on sex or race/ethnicity, consider hitting "pause" and investigating further.
You can use this OFCCP audit checklist to ensure you're doing what is required to maintain OFCCP's regulations including VEVRAA, Section 503, and EO 11246. Or request a demo to streamline your compliance and recruiting efforts.