I have two bunks on one side and the upper serves as a storage spot if it's just me and the wife out for camping. On it we put the DIY antennas, clothes, the shore cord sometimes, and bits of camping stuff toward the back that rarely is used. I'd estimate it at under 100 lbs. On the other side, the upper cabinet holds the microwave, underneath the vent hood, some plates and cook ware, misc. small items, around 60 lbs. of stuff.
I have Torkflex axles and shocks so my trailer is swung low. It rides like it's on rails and even big gusts of wind or hard cornering don't make it heel to one side or the other.