@Wesgilroyroughly 60 would be the max in a 180, however with that much room, I’d imagine you could have a thriving bottom dweller colony (plecos, corys, loaches, etc), if you kick back to about 40 pea puffers (41 if you’re Dean). I’ve never done this, so someone please correct me if I’m dead wrong, but I’d plant it fairly heavily and it could be tremendous with patience.
I did have 6 pea puffers in a 20 high planted and they were cool amongst each other, but they’re mellow ways ended there as far as tank mates. The problem I had with that aquarium was that there was nothing to roam around and eat the left over food. The above stocking idea would eliminate the problems I was having with my aquarium. Personally, if I had a 180 and wanted to keep a puffer species, I’d go with a much larger species, most likely a colony of Schoutedeni. However, to each their own and I think you could be on to something pretty cool. Good luck and post your progress, no matter what you decide to do.