I've had a 50 breeder before and it had a black center brace. You will not be able to go with one MH unless you replaced the center brace with something clear.
true to a point he would have to offset it or raise it and haave a little bit of a shadow in the center....I offset mine to one side about 4'' and had less of a shadow then I would if I put directly over the top.....But you are correct there will be a shadow of some sort if it has a center brace.