Could it be that there only ever were 49 people on the mission?
If the journey to the moon in a cavorite ship were nothing like on a rocket, rather a gentle float from Earth all the way up on a large, roomy space-yacht with no need for everybody to be strapped into seats and instead wandering around as they please, then "Uwe Fochs" may have been playing the roles of two people all along.
Four dozen is rather a small group for even an expert disguise artiste to pull that off, but maybe if the scientists and engineers are very focused on their own specific work and scarcely notice anything or anyone outside of it?