Well, this is an old discussion.
I already published my home built bottom fed Flarm (and ADSB) dipole antennas 2 years ago.
https://sites.google.com/site/threeu...flarm-antennas
By now, my antennas are painted black.

I personally did not like the bulkiness of the standard center fed dipoles either.
That's why I build my own thin "whisker" ones.
However, it has been discussed here in the past also already that the fact that humans have stereoscopic vision, means that an object like a Flarm antenna at 2-3 ft distance does not limit / obstruct the human field of view.

I cannot subscribe to Ramy's recommendation to put the antenna under the glareshield without knowing what is under your glareshield.
On my carbon ship, there is metal tubing structure right under the glareshield. Putting the antennas down in between that structure would significantly impact the performance.
In general, placing an antenna close to metal structures, like frames or metal housing of electronics boxes (radios, transponders, varios, flarm boxes, etc.) is a bad idea.
I needed to raise the antennas as high as possible above the glareshield
See images in the link above.
On other ships like modern gliders with a panel attached to a glass composite bottom shelf, this might be a viable option.

With respect to placing antennas on the side rails, you have to keep in mind that while the Flarm systems have an option for 2 receive antenna, there is only 1 Flarm transmit (and receive) antenna. And then there is of course the single ADSB receive antenna.
So, if you would place the Flarm Tx/Rx antenna on one side and the ADSB receive antenna on the other side of the canopy frame, you would get a skewed range diagram.
Difficult to say how skewed. Would be worth while an experiment with the Flarm range evaluation tool.

3U