See my warnings above in my last post. I will disagree with Fred a bit, as most radios are going to be in the 100w range, which have automatic SWR protection, reducing power if the SWR gets high (Poor antenna, shorts/arcs, etc). However, Fred is 100% right about the voltages present. My comment about avoiding metal near the antenna is ESPECIALLY important around things like fuel tanks, etc. Even a 10W radio can generate enough RF to give a nasty burn (don't ask how I know!) and could over time, compromise a metal item like a tank. As I worked for many years designing equipment to move gasoline around, we would test the units to see how a situation could cause an explosion or a fire. Some of those videos are scary. Static electricity is enough to set off fuel vapor. Having a slow drip from a wing tank and then having an RF spark would cause someone to have a VERY bad day. I've blown up enough gear to have a healthy respect for such things. As mentioned, a trailing wire is common, and easy to tune. Lots of aircraft have used them and it is current art, don't have to reinvent the wheel...for deployment/retract, you can use a cheap electric screwdriver to drive a plastic hub to hold the wire.
That said, the wire in the wings if run away from metal objects may work. A wire from wingtip to stabilizer to the other wingtip many give enough distance to work as well. I have tried many "compromise" antennas which can be made to work OK, but are truly marginal. There was an antenna that was marketed for an amateur radio "QRP" (low power) radio which made all types of claims how good it was. Science and math showed it to be a waste of money. I built a copy and never made a contact with it. One antenna set that would work well is the PAR end fed antenna, but you will need a 40-50 ft run of wire. It may work on the wingtip/tail/wingtip arrangement. Of course, nature is hard to fool and the more wire you can put up, the better.
The "BEST" in my guessimate is a 70-90foot long wire trailing wire, as most autotuners will handle that. Your internal wing antenna can be used for receive also, heck, you could d/f just by changing heading....! If you have the internal truly clear of all metal and no possible arc paths, and no tanks in the wings, I would at least try it. If you are planning to use such an antenna on a regular basis, I agree with Fred, forget it. The external wire will run rings around it, and be much safer for all except for the occasional bird....
Derswede/N4ABA