We have four 1+ acre fields, with 4-10 Labs in each.
The field with 10 has its own spring-fed pond for swimming (we had to run the invisible fence across the pond because some smartie-pants figured out that they could swim across and they were Freeeeeeeee!!!
We have the heavy-duty plastic kiddie pools in the other 3 fields so they can run through, sit in, lay in, play in, dig in, etc. cool water all day. I’ve found that if I can put the pools in the shade, I only have to scrub and re-fill every 3 to 4 days. If they’re in direct sun, I’m scrubbing and filling every morning because the algae grows like gangbusters. But I am extremely anal about water buckets (and pools!).
The flimsier plastic pools are too easy to puncture, chew pieces off, etc.
I know this is a bit off topic, but I am a firm believer in the pools. Some of our Labs don’t completely shed out in the summer. The really crazy thick coated ones we will shave before a heat wave (90+ degrees and 90%+ humidity), but even they are OK with access to the pool.
And yes, I think scraping the water off the coat as you would a horse would definitely help pull the heat off the dog.