Just curious what other folks have tried and what works without making an ordeal out of it??? Kinda hope to stay away from guide wires but that may be necessary.
Mounting to the roof means putting
holes through the roof.
I'd look for a way to mount to the side of a wall instead. The preferred mounting style somewhat depends on whether you can identify a stud location behind the siding, and how big the eave overhang is, but a mount similar in style to the image in the message above can be mounted to a wall.
Fifteen feet above the ridgeline is a lot, particularly if you ever have to take it down for maintenance. Personally, I'd use a shorter mast and accept that your wind data isn't going to be perfect. In any case, its also not going to be perfect at 15 feet above the ridgeline either.