What speed did you run the motor and would it last all night?
We had (2) batteries run parallel, the TM had 5 settings and we would use #3 most of the time, #4 if there was a hard freeze coming. We had a LOT of trial and error, we got (2) what I call swimming pool chemical buckets with the screw on lids, a 15" inner tube for each one to set in, painted the buckets black/brown. We tried romex the first few times, problem was that the colder the water the stiffer the wire become and it was white at that, hell to take up and move! We exchanged the romex for outdoor/waterproof extension cords, worked much better. Kept the bucket's handles on them to be able to transport. We hunt more river backwater than fields and had to devise a way to keep the batteries above water. Our field set up was the same, used the " T" post for the base, in the woods we would use a 2x4 painted black , wood screwed in between two trees .
The initial setup is quit a bit of work, once you get it going it sure does the job.