3 med supers are about the same brood/food area as the two deeps (ref.
George Imrie's Pink Pages). And only 40 lbs or so full.  I usually remove a
frame or two (prop on side of hive, after ensuring the queen is not on
them), then lift box over to the upturned top cover. Repeat on next box,
viewing whatever you need to.  If you can handle 40 lbs, then you can simply
seperate, smoke a bit and move the entire box at once.  Then, you can
install that screen board in about 10 min (ok guys, no laughing at the
weight challenges for average females here), rather than 40.  Mine are in a
deep and a med, but I may switch over to all Med, as I also have trouble
with that full box at the bottom if I need to do something underneath (which
isn't very often, I will admit).  Two are still on lath-boards over closed
bottoms, as I gave out the day I was changing them over. Maybe next year!

Also, there is a frame holder you can use on that spare box to hold 3-4
frames so that you can move the original box (use in addition to the spare
box, still keep the frames in the correct places).  I sometimes have lower
back pain, and straining against the heavy weights just makes it worse, some
days.  But, you can bet that if you strain your back while holding a hive,
you may try to put it down gently and in the correct place, but you are more
than likely to just drop it as you hit the ground yourself (and be unable to
move out of the way).

Karen