To address OP's original question about "weight limits", I don't remember who it was, but one member called Jayco about it because they wanted to re-purpose a compartment for batteries. They ended up bringing support down from the floor and across the bottom of the compartment using strut channel and threaded rod.
I think they said 150 lbs? But that seems pretty high to me. I just went through a couple of mine yesterday cleaning up some stuff. Maybe if the weight were spread exactly evenly throughout, but not for what I would consider "normal" loading.
-2018 Greyhawk 29MV
-1994 Jeep Wrangler YJ (Toad)
-2015 Jeep Grand Cherokee Limited (Soon to be Toad)
-2014 Jay Flight 28BHBE & Ram 2500 6.4L CC 4x4 (sold)