[euromodder]

* Put a splitter plate on the tongue to reduce crossflow between the towing vehicle and trailer. Could be a V-shape, or even a single vertical plate.

* Cover the wheels

* Build up the sides to the height of the front, and put a roof over it, at least as far aft as the fuel tank.

* if you can't make a roof, try mounting the fueltank lengthwise rather than transverse - frontal area will be a lot lower


In the long run, if you want to keep the trailer, moving the axles forward will increase its usefulness - unless you use it for very specific purposes that can take advantage of the rear axle position
(like transporting heavy gardening equipment, small crane , ... over the axles with the lighter stuff up front).