Well, time to make good. Once I'd decided to make it a single-panel object (as opposed to the half-a-dozen-panel-altarpiece-style assemblage I originally agonized over), I proceeded to order and pick up the supporting structure from my carpenter. It fit in my car with no problems, strapped over the reclined passenger seat and resting on the dashboard, and I remember thinking, "Geez, I could have ordered this another foot long, easy."
Then I brought it home, maneuvered it inside, and leaned it up against the wall. And then I remembered! As I had been planning, I hadn't made my car length the size limit, but rather, our apartment's ceiling's height. Good call, Cedra.
I figured out a sturdy but quickly strikeable easel solution--bless you, folding chairs--and then started doing loose outlines and color field blocking.
Aaaaaaaand off we go! Only a couple of weeks to work before I'm gone for a month (and then job hunting upon my return), so I'm motivated to make the most of it.