Ziptie and heatshrink is a good way to keep it safe and well positioned. Otherwise, 3D prints and antenna tubes I guess.
The fli14+ has rssi on channel 14, so you should be able to safely manage with one antenna. Just do some testing to figure out your range at different orientations.
I've had these in my Amazon cart for a while, ready to pull the trigger as soon as one of mine goes. You could cut the connector off and solder to the fli14+ easily enough. iFlight 2.4G Receiver Antenna with IPEX Interface Compatible with Futaba FrSky Silver-plated Feeder (20pcs) (non-affiliated amazon link)
As for soldering, you basically strip the outer layer of insulation, squash the shielding down and pull it to the sides, then strip the inner wire. From there, you've got the signal and ground wires to solder like normal.
yes it's a 2.4ghz antenna advertised to work with flysky that I got off of amazon. I did heat shrink mine like /u/pajamajamminjamie. Im going to try an unmodified antenna tomorrow.
I run DShot1200 on 32bit ESCs and don't use signal ground. I probably should. I just didn't feel like running the extra wire ;)
I feel like getting some thin coaxial cable might be the best option for noise rejection, though. Maybe I'll try that out this weekend.
EDIT 1: This oughta work: https://www.amazon.com/iFlight-Receiver-Interface-Compatible-Silver-plated/dp/B06XGH751J/ref=sr_1_1_sspa?ie=UTF8&qid=1511283014&sr=8-1-spons&keywords=2.4g+antenna+ipex&psc=1
EDIT 2: Actually, maybe not... I'll need to test for impedance.