Toolboxes for under the OEM tonneau?

Okay. This is driving me absolutely crazy. I have the OEM tonneau cover. I also have an Undercover Swingcase or whatever it's called. I've never been a huge fan of it, but it was the only thing I could find that would work. I tried the Du-Ha one and it sat too high, have looked at a few of the universal over the hump boxes and they don't fit much.

I had even talked to a friend about going to a bumper spare tire mount and fabbing a Ridgeline-like compartment under there. I got stuff that needs to go places!

I would like a side mount tool box that fits under the cover; or even on the hump. Is there such a thing? I thought I had found exactly what I was looking for at Northern Tool, but it's much too big. As a last resort, I'll go with the KB Voodoo box, but I'm still holding out hope that there's something I don't have to take out anytime I want to haul a bigger load. And go!