Originally Posted by DKB_SATX
Unless it's going to look wrong because of the height, you should leave a good amount of clearance so you can lift the trailer, work on the AC, be prepared in case you get crazy and buy a 345 MoHo, etc. It's easy to add a foot or two now, very VERY hard to do it once the thing is built.
Double down on the advice from DKB_SATX.
The picture below is what I put up about 7 years ago. I built this shortly after purchasing the 345. The dimensions are 16' wide (12' between uprights) X 56' long X 16' high (14' clear). I left enough height just in case there would ever be a 13' 6" MoHo in my future. The extra height came in very handy when I changed out the front AC on the 345 several years ago. I think the extra height also keeps the temp down a bit at the ground level.
If I had to do it again there would be some shade walls added - either solid panels or fabric. The structure is oriented North/South and in the summer the afternoon sun on the curb side is a killer.
For whatever reason almost ALL of the "RV Ports" at Texas Airstream Harbor in Zavalla, Texas are about 12' wide X 34' long X 10' high. These dimensions are simply not large enough for adequate protection. I have found through obversation that there needs to be about 5' overhang on the front and back to properly protect the unit from blowing rain and to shade the unit from the worst rays of the sun. 12' width is not nearly enough to leave adequate working room on the road side and at the same time leave enough room on the curb side for opening the door and a couple of chairs. I believe the clear 14' width I used should be a minimum for comfort and ease of use. On the height - I would not consider anything less than 12' clear - and even that would require insulation under the metal to prevent the structure from acting like an oven.
Every time I sit under one of those small, low RV Ports at TAHI I can't help thinking of Elizabeth Taylor after she said "I feel all the time like a Cat on a Hot Tin Roof" ... "What is the victory of a cat on a hot tin roof? — I wish I knew . . . Just staying on it, I guess, as long as she can."
Check out my signature line - "Suck it up, spend the bucks, do it right the first time."