Final Report:
Item one on my "Things I Forgot" list: My camera.
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The tent was labeled a 5-person, but they'd have to be awfully friendly. But there was plenty of room for the full-size air mattress (about 8" high) and all my stuff, and it was tall enough to stand up in, which made clothes changing much easier.
I learned that too many layers is just as bad as not enough. Flannel PJ pants and a t-shirt inside a sleeping bag and a wool blanket over all was way too much in the first part of the night, but very welcome in the wee hours. The temps got down to 42, and I learned that I can sleep with the bag all the way over my head.
I also learned that plastic zippers get almost as cold as metal ones, and I should sleep as far away from the zipper as is comfortable. I woke up at one point with my elbow against the zipper, and it felt like someone had driven a railroad spike into it!
I could tell that the air mattress was cool, but it wasn't a major problem. I'll pick up a something to put between it and the bag if I do this again.
I had fun, and I actually slept pretty well. Until the crows woke up, that is.
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Thank you all for your help!