We finally put together our "solution" and gave it a test whirl over the weekend! A few minor changes and I think we're solid! Thanks again for all the suggestions, folks!
For those interested, here's what we did:
- We ended up springing for the Disc-O-Bed, since we have a use for it after our trip. But I think our solution could have been easily made out of furniture grade PVC or another material as suggested by GammaDog.
- I cut the length of the cot to fit the dinette - I first tried it on the backs of the seats and quickly discovered that was not a good idea! So I got the leg extenders from Disc-O-Bed and re-cut the cot to fit snuggly inside the seat backs. The cot material scrunches up a bit, but not so much that it's a problem.
- I ended up buying a foam mattress for the bottom bunk and taking out the cushions. As I mentioned, this AS is on loan, so I'm not making permanent changes. The existing cushions needed to be seriously muscled in place as it was, and then with the added thickness of the cot legs it was pretty much impossible to fit them in flat. Plus, putting a foam mat on the bottom bunk had the added benefit of being thinner (more room between beds), and narrower (downstairs kid gets a little bedside "table", upstairs kid gets a step).
- I also sprung for a thin mat for the top bunk, but I suspect we would have been just fine without it.
- We found that the table easily moved and became tippy. I used two small "progrip rope lock tie downs" to lash the table in place.
- It's not easy to set up and take down. That said, it doesn't move, even in transport. This works fine for our family - we are tent campers used to using campground tables - but I suspect if we were used to using that table we'd have a hard time giving it up.
- The Disc-O-Bed is not cheap! But, it certainly is a solid piece of furniture.
Otherwise, I think it's a good solution to our specific situation (temporary loan of the AS, 6 week trip, and specific model). Hopefully this information is helpful to someone else out there trying to figure out how to fit more bodies into their AS!
Finally, here's a picture of the setup, with the kids (for reference, they are approx. 100 lbs & 75 lbs):