I was hesitant to use a tripod mount on my metal roof, so I fabbed up a mount for about $25 bucks. The nice thing about it is no chance of water leaks, the whole system pivots down to deck level for maintenance and it was cheap.
Materials:Sat dish J-mount - $9
8 ft length 1 1/4" T6061 pole - $16
Thin metal for shim (I had some rolled plashing made of some sort of tin/lead that worked perfectly. I think a person could use thin aluminum as well) - free
Assembly:Simple really. Remove the bracket off the J mount and install by predrilling holes and lagging to beam. They could go on a gable, or in my case a protruding ridge beam. Shim the tube and jam it into the J arm. Mount the weather gear on the arm. Drag it up the ladder and install the arm to the base mount. BTW, I did this with no assistant so it took a bit longer. If you had a person on the roof it could be a 10 minute job.
End Result:I mounted the anemometer higher than the bucket so that if I wanted to I could climb up to service the bucket and ISS. Now I can remove the bottom pin and pivot the whole thing for service. Seems to work right through my metal roof - 100% transmission.