Fellow ApolloHoax member Dwight is probably the best person to advise you. I've had a quick scan of the relevant chapters of his book "Live TV From the Moon" and couldn't find a clear answer. Weight restrictions in the spacecraft would have had a big bearing on what accessories could be carried. Apparently pills had been cut in half to save weight, but simple wire frames at the front and back of the top or one side of the camera might have helped.
Part of page 73 tackles the problem you mention:-
...there was a great deal of difficulty in aligning the camera so as to have the earth in the center of the frame. Bill Anders would later note, "For a while they kept telling us, 'Move it up' or 'Move it down'. We kept moving it the wrong way. In space, who knows which direction is up?" Capcom guided the astronauts, who in turn moved the camera in its mounting bracket and also physically repositioned the spacecraft to achieve the required framing of the earth.
Something else that would have helped is to work out in advance the exact language to be used when giving instructions for framing the view. All terms would have to be relative to exactly where the camera is pointing "now", and "up" would mean perpendicular to the top of the camera, not to the surroundings. So "move it up" would mean "raise the entire camera [a specified distance] but keep it pointing in the same direction." In fact, "tilt the lens up ten degrees" might have been better than "move it up", which wouldn't achieve much when it's already almost pointing at the distant earth, unless the transmitted view was partly blocked by the frame of a window or some other obstruction.
