I currently have a Comet NMO hatch mount for my 2M/440 antenna. I found out Larson makes a 11meter NMO mount antenna, how would this do on the hatch mount? I never cared about the efficiency of the location of my 2M/440 antenna as long as SWRs were low because I only talked on local repeaters. Would the Larson with the hatch mount compare to a mag mount Wilson 1000? Would not having the roof of the car as a ground plane be a problem?