Propane tank for heaters

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I use so little propane at our hunting cabin that the local Suburban propane distributor was trying to charge me a $150 penalty because they weren’t getting enough value out of the rented propane tank annually. I just told them to take it away, and I bought a 50 gallon tank of my own. Unfortunately, the new tank does not come with a pressure regulator which the rented tank had and I did not think to get any part numbers off of, so I need to identify which one I need.
Does anyone here know much about sizing these? Our cabin has three propane devices, two small heaters and an instant hot water maker. Each of them has a label that says they can use a maximum of 25,000 BTUs so all together the max load would be 75,000 BTUs.