We've been running those in rental fleets for years with no issues (unless you're jumping down from the bunk...which is why we put a ladder there).
The paneling is supported by cross members and the cushion itself distributes the weight. Unless you're climbing on it without the cushion, we have had 4 guys sitting there, all over 200lbs. I don't know that we have ever rated them...but you can easily add another layer if you're concerned.
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