All cargo-carrying vehicles (especially SWB because their angle changes more with the same suspension compression distance) should be nose-down when empty & nose-up when loaded to GVWR so that the average aim of the headlights is safe & usable. For non-cargo-carrying vehicles, or long-wheelbase (whose tilt doesn't change much regardless of loading), it's less-important.
This & the NEXT 2 (which are MUCH larger) diagrams show the factory specs for eBs:
(phone app link)