While I don't have any direct experience with THIS unit, I've spent a lot of time crawling around these smaller C's before buying our Airstream.
I always found that getting from a seated front position to the back was a pain. Could be done, but with some crawling. I suggest you go try it out for size to really know.
As to the A/C, I wouldn't count on it. Not to say it won't cool, but I just wouldn't count on it. This is a 13.5 unit, the middle of the road as to size, and only one. In the full, direct sun I would anticipate interior temps of 80 to 85. If I got 78, I'd be stoked. To that end, finding shade will be a priority. And it's all aluminum walls..and I wouldn't expect stellar insulation, not like some companies do. Shade from trees will make a major improvement.
Here's an owner you may be able to contact directly. New Coachmen Orion Owner
and I know there was an ignition switch recall on 16-17, so you'll want to be sure this was performed on any unit you take delivery of.