G'day Mate,
The Harrier flies very well, your idea about the antenna, is good, run it up to the top of the fin, push a pin through the end of about 1/2" of fuel tube, with couple of small slits in it, & pass the antenna through these slits, then push the pin, into the front of the fin.
Balance slightly nose heavy for the first flights, use low aileron & elevator throws, with duel rates set, fly on low rates to start with, & set high rate, so that high rate gives about 10% more than low rate, incase more control is needed.
And use a fine pitch prop, about 4" pitch would be good, but no more than 6". Prop diameter will depend on motor.
They don't need lots of speed, in fact they will flutter the control surfaces if flown too fast.
And last of all, & I'm sure you will anyway, get help, even if it is just to have some moral support for the first few flights.

Above all, enjoy, that's what it's all about.