Here are lows 24 hr fars with #1-AC powered over grass, #2-20' DC solar on battery anemometer mask, #4-DC powered on battery over bare/dead grass. Both 1&4 6' mounted shields lows 64.7. #2 at 20' 65.0.
The 20' shield was only .3 warmer. Light winds overnight played a roll I'm sure.
So there you have it after first full day of testing, daytime highs significantly cooler at 20' around 2° on average, nighttime lows hung about a degree warmer during most of night but toward daybreak came within .3F.