Hei Tor,
I would NEVER fly my jets on an internal or parallell to the fuse antennae on 35 MHz. I know from experience and testing that you can do this on 72MHz, but here in Norway where 35 mHz and 40 mHz are the allowed freqs, whip is in my opinion the only option. The funny thing is you can have an installation with a hidden antennae giving you reasonable range and everything looking swell, but on the 20th( or whatever) flight - PCM lock or PPM shakes. I only know that after we started with the whips, the number of radio troubles were reduced to almost nothing.