I worried every single night that I would make a wrong move that would finish off those beams and send us plunging down onto the floor. It has happened before, and I'm still near my fattest weight ever, so I was paranoid.
By the time Friday rolled around, I couldn't let it go any longer, so I sent Jason off to get some wood and a saw. We cut our wood into some cross beams and supportive feet and then the construction work began. First we tried to drill screws through the beams into the feet, but the drill bit just stripped the screws because it wasn't the right size. Strike one.
I suggested nailing the feet on, instead. Jason went out again, bringing back nails thicker than I have ever seen in my life. An excellent idea, the nailing was, except that the nails got stuck and wouldn't penetrate the foot pieces, and all of my pounding and whacking with the hammer just bent them at crazy angles sticking out of the beams. Strike two.
Then Jason finally realized that he did have the right drill bit after all, so we screwed the feet on as planned.
We haven't heard a creak out of that bed since.
Here it is before (with one support beam laid across, and you can totally see how the one flimsy beam in the middle is bowed) and after:
I'm putting this project firmly in the "win" column.