The fold down packing chest type seems like a good idea to me.
I've found to my cost in the past that what seemed like a good idea
nailing/screwing things onto the brood box in mid season with plenty of
supers in place, became a real problem when the supers were removed for
winter and the telescopic roof wouldn't go over the additions on the
brood box.
 
If you do decide to add bits let me pass on a couple of "nailing" tips
given me by an old NE Scotland farmer-
    -If ther's any risk of the wood splitting, blunten the nail by
giving it a sharp tap with the
     hammer on it's point with the head held against something
solid-this makes it cut
    some of  wood fibres as opposed to forcing them apart.
    -Always drive the nails in at an angle (20 or 30 Degrees) so that
they don't pull out so
     readily-opposite angles time about if there is a row of them.
   - If your nailing on e.g. a piece of wood which is going to act as a
handle,angle the nails
     upwards so that when the handle is lifted it tends to pull the nail
further into the parent
    wood of the box.
Happy honey hunting
Alan R