Debra Sharpe has trouble in lifting a full size box (presumably Langstroth)
full of honey. I have occasionlly had the same problem when the bees have
filled a national box with honey - it seems to be glued down at first. It
must be one of the causes of beekeeper's back.
I suggest Debra could solve her problem by lateral thinking. Instead of
having 20 frames in 2 layers of 10, have them all side by side in a single
layer. Of course, it will mean breaking with convention and also doing a
little carpentry, but, hey, why follow the herd. You have nothing to lose
but your truss.
Chris