Good question on the height issue. I am 6'3" also.
The height of ours is 78 1/2 inches at the center and of course, that decreases with the roundness of the outer shell. I have no problem navigating around but have to pay attention to the light fixtures and door openings (the two interior doors have a header height of exactly 6 feet). You just learn to dodge and duck.
I have always said it is a 5-10 world--everything is made for average sized people and us folks with a few more inches in height just have to work around those standards.
The Airstream has a different feel inside--like an airplane fuselage or a boat cabin--the feeling is not like a square box, for sure. I like that feeling, though. I also like the relatively smooth aerodynamics of the trailer and the great towability, which greatly offset the small compromise of interior headroom.
For me, the place for greatest potential for forehead contact is the entry/exit door. I have popped my noggin a few good times going out. You just have to pay attention.
Please let us know how you decide.
Easily distracted by shiny objects.