I plugged in the numbers for your 80-meter dipole (using EZNEC)
for an apex at ~30 feet, freq of 3.550 and sloping legs of 63 feet
to 15 foot posts, an inverted V shape. Your (this) patttern
looks classic NVIS. VSWR was about 2.8 and the resistive
portion of the impedance was 23 ohms. I wouldn't change
a thing. Assume you use a match at your rig?
My 40-m NVIS dipole has the same classic NVIS azmuth pattern
but has 32 ohms resistance at the apex coaxial feed. Not much
difference, just a VSWR of about 1.9 to 2.1. I use the match inside
the FT450D to get the VSWR down to 1 to 1.
Unc Phil, W0XI