A while back I started doing some research about how to mount the Maretron WSO100 weather station to the masthead. The yard had recommended I use a piece of flatbar and I went as far as ordering a piece and roughing it out, but that approach really bothered me. First the instrument would be directly at mast height level and I felt it would block the nav light too much. Secondly I was concerned it would be low enough to snag the spinnaker.
This weekend while rummaging around Second Wave I happened on a Glomex V9173 TV Antenna bracket (look around prices online range from $30 to over $100 for new ones) to which I attached a Shakespeare extension mast. The whole thing cost me about $40 since I bought everything at Second Wave. This setup avoids the problems I mentioned above and the whole thing weighs less than the flat bar. I still need to make or find some grommets to protect the wires where they exit the mast, but my wiring projects are coming along nicely since I was able to solve this problem.