Here is how you can get about 22-23 gallons post boil. After the mash and you begin the fly sparge or batch sparge(whichever you prefer) start crushing your grain for batch #2. As batch #1 is boiling you will be mashing batch #2. As batch #1 is done boiling transfer into fermenter and remove false bottom of BK and clean out hops and hot break, replace into kettle and begin sparge. Doing 2 batches back to back will only add 1.5-1.75 hours and you only have to clean the entire system once. Heck, I leave PBW in mine overnight and it comes out clean as a whistle. It takes 1 or 2 times to get the timing down but 2X the beer and only cleaning the BM once..............priceless.
Good luck if you pull the trigger but you can buy some 4 BBL if you're willing to piece it together.
Good luck if you pull the trigger but you can buy some 4 BBL if you're willing to piece it together.