You guys are spoiled
99% of the jobs we are on we can not hang a 4" square off the bottom chord of a truss or I-Beam.
It is almost always in the specifications that no loads are to be placed on the bottom chord or web.
If it is an I beam structure this means using threaded rod up to the top web for even small single raceways on minnis.
It has always seemed a little extreme but it keeps it easy to enforce, no fussing around with figuring out what is to much and what is OK.