Not sure how much you were joking about, but how do you run out of hot water? We've done all that in our house and the water in the tank just gets hotter the more you use it. Are you serious that you run out of hot water?
Serious as a heart attack.
Using a side arm, power vented 40 gallon water heater, couldn't get the top of the sidearm low enough. Seen no higher than 4 inches maybe? I ended up almost six. It does work, just not as well as it could I suppose. You also haven't met my wife, she looks like a damn lobster when she gets out of the shower, how she can stand it that hot is beyond me.
I also use a LOT of hot water in the winter. We use glycerin, jam and even maple syrup in the rations for the beef cows. It gets cold enough and the solids in all of those will settle out, only way to get em mixed back up is to add a lot of HOT water and agitate, I usually run out of hot water before I'm done. The hose is hooked right to the pop off valve at the top of the water heater.