Welcome,
I had a hard time searching here in the beginning...there are so many good designs, and users, many have posted builds and don't come back...must be enjoying their trailers!
Here's mine, a half-wall removable "closet" for a window A/C on a barn door trailer. The wall clips/bolts into brackets mounted to vertical e-track so it can be removed during cooler months.

My buildup is at the bottom of the first page here:
http://www.tnttt.com/viewtopic.php?f=42&t=49438Here's some of my other favorites:
From kstephenson

From jwhite

His entire wall is hinged on the left side and rolls away to make room for a golf cart.
From WA
http://www.tnttt.com/viewtopic.php?t=40504I can't say why, but this is still one of my favorite builds, must be the cabinets/color and ceiling treatment. I got a lot of inspiration from this one.
Also lrrowe mentions the removable and pass-thru options, this is huge for us, and we use it all the time. We most always cooked outside before getting the trailer, so we still do. nice not to have all the cooking odors in the sleeping area.
David