I would not put anything heavy up that high period. Clothes, small light weight items paper products is about all that should go above the waistline.
I use the overhead storage for wine glasses, paper plates and cups, my dogs toys, napkins and tablecloths.
Keep in mind that the effect of the weight in the top is magnified by it's Lever Arm...reacting against the force of the frame wieght and lower weight of the trailer, that lever arm increases the effective weight of the items up high.
It's not a good idea to put any significant weight up above the waistline of the trailer.