Don't think it can be done. Mounting the dinghy vertically will mean the bow is at least 8' above the waterline. Horizontal is possible without the Hydrovane. Snap davits will not work as they need a platform for the dinghy to land on - they were designed for MOBOs that have a bathing platform but can work on some yachts with a wide sugar scoop. The only practical method (without the Hydrovane) is a pair of swivelling, removable davits such as Plastimo and Cooney sell.
BTW how is your Hydrovane mounted?