A "Mouse Hole" is campers' slang term for an access hole with a hinged lid that lets you pass the large end of a cord through between inside and outside, and then close it. A sliding cover slides up to expose a notch in the lid that lets the cable through run through it when closed, or slides down to seal the notch for travel, boondocking, or storage. I suppose mice can run up the shoreline from the ground and sneak in through a large opening if it is left uncovered, hence the name.
Camping World lists "cable hatches" for $5.55 for non-members of the discount program:
I think you have the right idea, but the term "receptacle" to those who work with electrical wiring means a female outlet. You always want the female on the source or "hot" side, and male pins on the "load" side. That way, there is never a case where you have exposed metal pins with power on them when the cord is disconnected. If you still want to tempt fate, you need to stick a paper clip or screwdriver into the holes or slots of the receptacle to electrocute yourself.
You can't electrocute yourself (or an unsuspecting friend who wants to help you set up) just by accidentally getting your thumb on bare male pins when picking up the shoreline.
If you can find or fabricate a connector with male pins to sit behind your cover, great. That would be the way to go. Because of the cost, a cheaper way many choose is to have a cord run through the body instead of a more expensive fixed connector on the surface.