I'm looking at doing the same thing, even though my aircraft won't even be delivered until late next year.....but you gotta have a plan

The Eurofox (normally) seems to have a TED-type antenna for the transponder, similar to this:
http://www.aircraftspruce.com/catalog/avpages/ted_transponder.phpThis appears to normally be mounted underneath the seats and has a pretty decent sized aluminium ground plane. I have asked for an extended ground plane to be fitted when my machine is eventually built. I envisage this being in the same place beneath the seats but running the whole width of the aircraft. To this ground plane I hope (assuming my plan is sound) to fit another one of the antennas above for the ADSB reception of PAW. For symmetry I would like to mount it on the opposite side of the aircraft to the transponder 'TED' antenna but that might not be possible if someone tells me it'll interfere or some such. Between these two antennas I would like to mount one of these (I've already ordered it but awaiting delivery):
http://www.gps.co.uk/antenna-exterior-gav-868-flarm/p-0-2024/This antenna will be used for the P3I part of the PAW.
The power supply to my PAW will be via a Charge4 USB charger and it'll have a Bluetooth transmitter plugged into the jack to give me PAW audio through the headset Bluetooth connection. If the GPS dongle is unable to do its job because it is hidden behind the panel and underneath the coaming then I shall connect a GPS mouse and probably mount that atop the coaming and well forward, where I can't see it ruining my minimalist panel.
All very pi-in-the-sky (yes, I deliberately spelt it that way because I am being a smart-arse) but that is my basic plan. If the two TEDs outside is a no-go then I'll use the supplied ADSB antenna inside the fuselage and just have the P3I and transponder antenna externally mounted.
As for the actual physical mounting of the antenna, I reckon if the existing ground plane is man enough to take the normal transponder antenna with no special brackets, then an aircraft-wide bit of aluminium should suffice for a total of three aerials.
I welcome comments on what I'm doing wrong or for flaws in my plan
