Buck wrote:
. . .
If I hang the vertical here, the top will be about 65 feet above
ground. The dipole feedline will be about 15 feet away and the center
of the dipole about 50-55 feet high. I doubt they will interact with
each other.

The dipole feedline and the vertical will interact a great deal unless
you take steps to prevent it. That would be to insert one or more
"current baluns" (otherwise known as choke baluns and common mode
chokes) in the dipole feedline.

Roy Lewallen, W7EL