Leaving a plain, insulated stud wall that has a panel framed in that just pops out (needs to be a tight fit) is more inconspicuous than sheetrock with seams, hardware or other tell-tale signs of an access.
Not to mention an unfinished frame wall is as normal in a basement as a finished wall would be...........do you see the access point??.........it has been finished inside now and has a stack of empty boxes and a bar across it with coats hanging in the way......just slide the coats over and push the correct stud and the door pushes in.....it has a lock hidden behind the insulation and the closet door locks from the inside for when I am inside
Sorry the pic isn't rotated.....also I changed the door to make it an outswing like a normal closet would be......