I haven't had the chance to camp in my Outback yet - I've only had it since Dec. 1st. However, I camped a great deal in my 2004 Murano.
Never had a condensation problem with windows cracked. I'd cross-ventilate with at least two windows opened about 1.5-2". You can pop the sunroof open too. Might want to have a tarp in case of rain to throw over the roof & window area to protect the openings, or maybe rigged to hang from the roof rails, if you don't have the optional rain guards.
Of course, you are limited with gear space inside, but there's always been enough room for me and my gear when I'd be off alone, even when I'd be gone for a couple of weeks. My mountain bike would be locked to my roof rack. I'd keep a couple soft carry bags with lots of pockets, and lay them on the bed, along with a little other gear. Also, I don't need the whole bed, so I'd put some items off to the side down by my legs. I guess it would have been nice to add photos showing all that, but this was enough work already - I mainly wanted to cover the sleeping setup.
A twin bed would give you more storage height in the back - though I've found the double very comfortable to sleep on, and can easily toss gear around it. I had a double AirBed anyway, so as long as it's working for me, it's fine.
Once I'd parked where I would settle for the night, I'd transfer the bags to the front seats. I'd also stash a lot of gear on the floor of the back seating area, and on the front passenger side floor.
Camping in an SUV isn't for everyone, and it can be a tight space for two. But it can also be streamlined and convenient. I used to do a lot of backpacking and tent camping, but I've found often much more convenient being self-contained. If I'm out after dark, say like messing around up at Lake Tahoe 'til late, maybe at a restaurant or bar or casino, I can drive right in, almost completely set up. No tents to pitch and sleeping bags and pads to lay out in the dark, and not catching those rocks you would be sleeping on top of. I don't always feel comfortable leaving my pricey gear laid out at a campground all day while I'm gone. Being self-contained, I don't have to cut into my day to get back to the campground to set up.
The other side of "camping" in the car for me is to save on motels during long trips. When I'm with my girlfriend, I don't mind spending the loot, but I hate to spend about $80 or so just for me, when all I need is a place to sleep. I'll usually stay in area designated for overnight sleeping, but rest stops and quiet neighborhoods could do in a pinch. You certainly can't do that with a tent. If I ever was to get hassled, which has never happened. I'd just say I was driving a long way, got very sleepy, and considered myself a road hazard if I continued.
BTW, if you're in bear country, your food shouldn't be stored in your car anyway. I friend of mine had her car door torn right off by a bear going after her food in Yosemite Valley.
