You kept one of the heaters... what's gna go over it? What's that reflective stuff underneath?

The reflective stuff is just a leftover piece of insulation. I put it there to keep the heater from poking the new insulation until I could get the OSB down.

Once the OSB was installed, I put a few seats back in, including the one that sat over the front heater.

I modified the seat frame to support the rear heater, then buried in my bed frame. Hindsight and all that, I wish I'd removed the rear heater as I never use it, but I'm way too lazy to rip the bed frame apart and start over...