If you haven't gotten this far in your build yet,
I see no reason why this wouldn't work for Com 1. My Com 2 will be a belly-mount actually on a an inboard wing inspection plate. Obviously not yet flying - but in theory a quarter wave stuck to an RF-transparent radome should get out just fine. That's a quarter-wave of copper foil in the left foreground. Feedpoint will be grounded on the right longeron.
While we are at it, why not put the VOR/ILS Vee in a similar spot and feed it with a coax balun?
No one will ever poke their eye out on this dipole, nor get tangled with it while cleaning the belly. It's a resonant half-wave dipole and extends a ways down the doorway B-column areas. 26" per leg.
I haven't yet trimmed the comm "whip" to resonance, needing an antenna analyzer to do so, and with the cosmetic paint in place I hope it won't need trimming (yeah, right). The antennas are completely invisible and zero-drag.
One thing I'd do differently: cut the antenna shorter than formula length and bring it to resonance with a little base-loading inductance once installed. As it it, if I'm long, I will have to shorten it with a razor knife through the paint "by feel," or with a series capacitor at the base. Finding a suitable silver-mica cap to electrically shorten this thing could be a bit of work, and I wish I'd thought to go too short to begin with
Hop-Along Aerodrome (12VA)
RV-6A - N30YD - flying since '98
RV-10 - N130YD reserved - under construction
donating monthly to the VAF - thanks, Doug