I drilled holes for the hinge and dimpled them with my pop rivet dimpler. I drilled holes and attached to platnuts. Primed and painted the platform. Mounted it to the firewall about 2 1/2 inches below top of cowl.
This will hold both antennas. It is easily removable if necessary. But might not need to come out. Oil filter is very accessible and removable without taking out this platform.