Okay, so here's a slightly-off-subject follow-up. I looked thru
cebik's web site and didn't see this addressed: Since the G5RV isn't
particularly resonant on 17 and 15 meters, if I connected a dipole for
each of these bands, in parallel, at the same feedpoint as the G5RV
would this work effectively?

Way back when, I recall putting multiple dipoles at the same feedpoint
without incident, but I haven't really seen this discussed much.
Intuition suggests that they would interact negatively and impedance
would be wacky.

-Chuck