If the tank is correctly built, it'll have a 'standpipe' sort of a drain bolt located in the bottom. Any sort of standpipe is OK whether it's the drain bolt or otherwise. Once enough oil collects, if the tank isn't emptied regularly, it'll drain over the standpipe. That prevents blocking the airbox drains. At highway speeds, airbox collector oil will cover your coach backside.
A worn engine can fill the can quickly. Regularly drain the tank and you'll get a feel for when it needs servicing. Doesn't need cleaning, just emptying.
I need to check mine....sorta forgot about it.