Bed?  Heck  put a ladder up the side of one rack cab.
and throw
 the mattress on top of the cluster of racks! 
With talk like this, anybody want to admit to having a floor fail out
 from under their collection?  This stuff Is heavy.
Personally I'll admit to having a few 1" deflections here and there.
Nothing worse.   Yet.  <g>
John A.