I decided to mount the ELT antenna in front of the vertical stabilizer. There is a 1.25 inch space between the end of the Canopy skirt and the start of the VS which is about the only place to mount the ELT antenna vertically. Some have mounted the antenna horizontally between the HS and VS underneath the fiberglass fairing. This is not acceptable to me. The location in front of the VS is not ideal but its the best that I can find.
Constructed the doubler from .060 2024T3 and rolled it to match the shape of the upper skin