[jrfiero]

First post from a lurker.
I searched around, but if another thread answered my questions, please point me to it.

I tow a Haulmark Transport 5x8 enclosed cargo trailer (haulmark dot com/bumper-pull_cargo-trailer/Haulmark-TS-5wide/Haulmark Trailers - Cargo Trailers - Bumper Pull Trailers - Transport 5' Wide) with a 2013 Lexus RX450h.

It's a tall box with airbrakes for fenders, and it kills the hybrid's mileage (17mpg loaded, 18 empty, vs 27 wo trailer). Its only attempts at aero are a gently rounded front and radiused front corners.

I know there are many things I could try, but I'm looking for quick improvements.

A NoseCone is too expensive and requires customization for the 5' wide trailer.

A v-nose is too much work for my available time.

A full belly pan doesn't look too hard.

These vortex strake devices (ecomodder dot com/forum/showthread.php/vortex-strake-device-reducing-aerodynamic-drag-26123.html) would be simple with some aluminum angle, but I'd just be guessing at size, and it's debatable whether they work anyway.

Some sort of trailertail device (atdynamics dot com/aero.htm]Aerodynamics 101 - Tractor Trailer Aerodynamics | ATDynamics) would probably be the biggest bang for the buck but it'd take me a while and it would all be custom.

So those fenders are killing me, sticking right out in the way. I was thinking of fairing the fenders back into the body at their rear, from the top and outside of the fender down to the lower corner, with the side and bottom of the fairiing closed. Thinking there's more to be gained at the back of the fender than the front, if one were to choose. The top of my imagined fairing would be about at the same angle as the vortex strake devices above!
I'd do the front of the fenders differently (and later), with the top of the fairing remaining level with the top of the fender to the front corner of the trailer.

Moon discs (probably not pizza pans) on the outside of the wheels, stationary pizza pans inside the wheels (attached where the brakes would be if there were any).

Can't do a flat fender skirt because the tires, surprisingly, stick out beyond the big fenders.

Mods to the tow vehicle are. not. allowed .

Thoughts on which would give the most benefit for time spent?

Thanks,
Jonas