20 gallons is pretty big. If it were me I would NOT exchange down to the 5 gallon brewery but I would go to a 12-15 gallon kettle and start brewing double batches x2 the beer in roughly the same amount of time. Unless you have a great pipeline set up and 5 gallon batches are just fine for you, then and only then would I down size to a 8-10 gallon pot. (and possibly weasle in some other needed equipment.)
“I'm not drunk, I'm from Wisconsin.”
We have been out drinking your state since 1848!