It has more to do with the surface area of the top and bottom of the camper. If the top of the camper has a higher surface area than the pressure over the camper will be lower.
Look up Bernoulli’s Principle.
I studied Bernoulli’s Principle (just a day or 2, IIRC) in my college Physics course. :-)
And, as I said, I went to various sources online (NASA, Model Plane forums, etc.) The subject gets complicated quickly. But I don’t need a precise answer - just a rough “back of the napkin” type estimate would do.
That said, from what I do know, it looks to me like the shape of the camper would cause a slight downward force, and the design for that may be intentional. But, really, this thing’s cross-section is more like a block of wood with slightly angled / rounded corners, than a wing. And then the “front” is tilted up...