Hello Beetle5 - welcome to Air Forums! The air conditioner hanging down is too close for comfort at my 6'0". Ducking has become 2nd nature.
A good forum friend sold for something other than an Airstream but we still see him online here. He is 6'5" and has discussed this any number of times. Here's just a couple:
We either get electric plug-in only at state parks or dry camp (common in state or nat'l forest campgrounds). Either way gray tank capacity doesn't allow a lot of showering. In state parks I'll put on the ol' flip-flops and use their shower. In quieter campgrounds I'll use the outside shower to freshen up; that's not Susie's favorite way of doing it however...
In shorter Airstreams bed space is pretty much limited to the corner arrangement or a sideways bed at trailer front or rear. The sideways bed is longer but only 48" wide. I don't think you'd do well using just half a corner bed. Good friends just purchased a 23' International. She (5'7") is going to use the corner bed. He (5'11") is going to use the couch pullout -- that's about the same as the couch on my 25' FB Safari and it works fine for tall.
Twin beds in almost all Airstreams I've seen are equivalent to dormitory tall single beds. We have that in our Safari and there is very good length. We use dorm tall single sheets from JC Penneys, etc.
Good luck in your quest.