Suggestion? Corn Field - PTT Headset - Rechargeable

From those much more in the know, I was hoping for some suggestions. I’ve read a lot of posts and think I’ve confused myself even more.

My wishes/needs:
-PTT via Headset, either inline or main radio PTT (no VOX needed)
-$500 ideal budget
-12 radio/headsets
-belt clip capable
-5-6 hour runtime
-Work in corn field, covering about 5 acres. Straight line distance should not exceed 1/2 mile.
-Weather resistance (but will not be dropping in standing water)

Background if it helps.
This will be for a non-profit corn maze, used by the staff spread throughout the area. Most important is the security staff inside, who can easily be in damp/dewy corn and damp dirt all night long.
We used to use 5 Motorola MagOne business style radios, but those are no longer available to us. These did above and beyond the area range we need.

I was looking at the Uniden and Motorola series and it appears the Motorola has many more interchangeable accessories. I don’t know if it’s worth paying the extra money for the waterproof models.