In an above ground installation, Hustler recommends a minimum of 2
radials for each band. That's 12 wires, the equivalent of 6 dipoles.

Now, I'm wondering, why bother with the vertical section at all. If I
put a PVC pole up 25' (the height of the 6-BTV) and tie all the radial
pairs as inverted vees to one feed line at the top, wouldn't that work
as good. What effect would the feed line have on the radiation
pattern?

The dipoles would also serve as guy lines.

Maybe a balun on the top?

I have had inverted vees in the past and they seem to work great.

Ron, W1WBV