Here are a few potential trailers that  CornPro may be putting into production soon.  Drop down windows, swinging saddle racks,  and fully enclosed sides may soon be available. 

CornPro and Moritz's Slant Load Combination Trailer is a convenient way to haul your horses.  With a moveable divider wall, and slant divider, you have the flexibility to use the trailer for more than just animals.  Available in 2, 3, or 4 horse models.

It's good to keep in mind that many "horse" options are available for stock trailers as well.  Here we have pictured a gooseneck stock trailer with a solid side door, and windows in the neck.  Also pictured are the butt and divider bars inside a livestock trailer.