Sage Marine uses only the Garhauer Marine (Catalina Direct) mounts. Although Garelick, the original supplier of "2 stroke" mounts for O'day has since updated and made new mounts for 4 strokes, from what I've seen and discussed with the former production manager of Sage Marine, if I decided to replace my mount, I would only go for the Garhauer mount. It is very well built and smooth working. Because it is available with different spring configurations, it can hold the weight of almost any small outboard for a sailboat.
I'll also second the notion that you should go for the longest shaft motor you can get, which is usually a 25" shaft, often found on "Sail Pro" model motors. The other usual sizes are 15", and so called "long shaft" at 20", but for a sailboat where you want to keep the prop in the water and driving at all times in steep, rough seas, the 25" shaft is recommended.