CoverMate 3 deckmount is usually the best one.
kingdarb: the standard CoverMate 3 would work a little bit better for your setup. If the cover not going all the way back bothers you, you could unmount the CoverMate 1 that you have, and install the standard CoverMate III, which holds the cover more upright and doesn't fold behind the tub like the CoverMate 1. The CoverMate 3 would cover most of the holes left by the CoverMate 1, but you may have a few that wouldn't be covered by the CoverMate 3 bracket.