I installed mine on a post mounted on the boomkin. There were a few reasons why I did it this way...
Installing it on the mast required a lot more work to get the cable to the screen and also the windage issue aloft. Also would be a pain to work on if I ever need to.
I wanted to put it on the backstay with a self leveling mount but those are extremely expansive mounts!
Finally the post on the boomkin keeps it fairly low for the windage issue and is easy to get to if work needs to be done... and the post can double as a wind generator pole. The post from Garhauer marine was very reasonable and they will build custom mounts if you need them.