For anyone interested in adding AC and a heatpump to a vintage airstream, I found two cool
options that don't interupt the trailers exterior lines. One is a daikin mini split system which has a ridiculously high SEER value, I think around 16 SEER the highest efficiency I've found. It also doesn't use Freon, but rather the new coolant which is safer for the environment and many environmental agencies are pushing for the switch to. Basically if I lose the battery box behind the propane tanks on my '62 Globetrotter and switch to a blue top that is safe for inside the trailer, I can locate the condensor behind the propane tanks. The fan provided I'm willing to lose part of the front bulkhead fits right above the dinnette at the ceiling. Also, the two lines that run between the condensor and the fan are only 3/8" and I found out can be fished through the wall, which I tried with electrical fish tape by removing an electric cover plate at the dinette and exploring. No holes or messy visible lines. The liabilities of this system is that even though it's incredibly efficient, it still will require a generator (I was thinking of two hondas run in tandem.
The second option is a 12volt swamp cooler, so retro, small and sweet looking I almost want to buy it just because of that, see http://www.swampy.net/ac12L.html
The man I found to be the most helpful and knowledgable with all this AC stuff is an engineer named John who works for or owns www.acforsale.com
He's got lots of ideas beyond what you might see in their online catalogue and a great sense of humor. Check out the pet cooler he showed me: