So there I was thinking. ( A dangerous thing only slightly safer than a nuclear melt down )

Your drop is a nice sheet metal modern look. SOOOOOOOO Several snaps 6" out or so surrounding the door. Then a canvas or even a silver sided heavy plastic tarp cut ( and hemed ) with snaps added to snap an upside down horseshoe shape around the door. ( HMM can be same profile shape as the door as I think on it a second more. Then the material comes out perpendicular from the trailer whatever distance you like ( using 5 feet as a number ) then a piece across the horseshoe tube at the end with a zipper in the middle to close it off. As you have a straight lines trailer, the tube could be squared off as well using PVC with elbow joints.
Geez now you want supports.

OK think hula hoops cut in half to a semi-circle to form an arch ( heated and bent PVC would work ) then straight poles to the ground. Loops with velcro or snaps on the inside at 3 or five points to secure the support hoops on the inside of the 'tunnel'. Anchor loops on the out side to tie cords to ground stakes as you like.
OKAY now you wanna store it, ain't you just so greedy and needy.
Two pvc tubes under the trailer to slide the supports into. If you 'tunnel' is about 3' wide or so and if your wheels are mounted towards the rear then the tube could go under the back end. if the tubes are set back a bit then the curve sections could even stay on. Just slide the poles into the tubes. If you did square with pvc and elbows then just pull the support pipes out of the elbows and easy to slide em all in a few tubes under trailer.
Good grief , do you not stop?

OKAY so your trailer is not square or round. Then use 45 degree pvc elbows and go for a gambral roof support look but with only 2 sets of elbows not 4. Kinda of the barn roof look.
What now you are worried about rain at the door dripping on your head as you exit to do what ever you do in the tunnel? I swear some people just want EVERYTHING!

Okay so you make sure your tunnel snaps are under the rain deflector over the door.
What you are 7 feet tall and hate to duck? Just make the sections of supports get taller as it gets away from the trailer.
Heck say at one foot out you could do a sudden straight up as high as you want but have to sew in a vertical panel to go up to meet the new height.
Yes you can use a can of spray stuff from the sporting goods store to waterproof the light canvas. If you are using a silver sided tarp, most of the heat will be reflected off. I would still plan on some built in air slots, perhaps with bug screen sewn in. Because it is not a ridged solid structure, an uneven ground won't matter. Just make sure you plug or put caps on the ends of the pipes to keep mud and dirt out. Put in what ever you were using before outside the trailer to keep mud out and you will be good to go. Even artificial turf rug will do.

Ok that's it, a wrap people. Take lunch.
