They draw from inside but, if the cover is in direct sunlight or it's just hot outside, it may slightly warm the air inside the unit. You MAY be able to run both AC units on 30A the same as you can run a single on a 15A circuit. You just can't run much of anything else and you don't try to start them both at the same time. NOTE: some people will tell you not to...the reason being is that if the voltage drops below a certain level it could damage the unit. That's mainly a concern in campground type settings that are getting heavy usage (many users / high temps / etc.). I just bought a HW50C to install in the new trailer so, if I run into that situation, it'll just kill the power.
2012 Chevy Tahoe LTZ - HD tow package
2017 Rockwood 2703WS Emerald Edition