It's hard to tell from that angle
but suppose the front and rear slopes are oriented so that surface normal vectors point toward the axle. Then any pressure drag -- positive in front, negative in rear -- lacks any fulcrum leverage to apply "pitching moment" going down the road. Tongue weight then does not change with speed so a trailer balanced at rest stays balanced at highway speed cleverly avoiding potential for speed-induced sway which characterizes and plagues so many enclosed trailers on the road. European campers seem to apply this lesson regularly, perhaps due to smaller, lighter tow vehicles (compacts and subcompacts), and also indicated by typically aiming for 7 rather than 10 percent tongue weight as a minimum. In the US where heavy trucks and SUVs dominate, as reflected to some extent in fuel prices (ie, demand) few trailer designs seems to heed this design knowledge. But some do and this Montrose seems like a possible example. It may not be aero for FE but aero for safety is a very good thing that deserves attention.
