OK, I admit... I'd never even thought about swapping the access door around until I saw your post. I decided to tackle it this morning.
Pretty simple except for my old knees... took about 15 minutes. While I had it off, I decided to snap a few photos for those above who were asking about it. Just an empty cavity in the dovetail. Not sure if all rigs are the same, regardless of whether there's a door there or not. For those who may be brave enough to find out, I snapped a photo of the parts tag on the door, in case they may wanna look into getting one.