Beets in a stew? I haven't seen or tasted that. Is it just a meat, potatoes, carrots type stew?

I have thought of what may be an easier way to deepen your beds.
dig a hole!

Dig a hole, mix what comes out with a lot of wood chips (lots of green stuff too, if you can get it) then put it all back in the hole, and put a raised bed thingy on top of it.

It might be easier than trying to make those metal things twice as tall.