Rocket Oven perlite base?

I am removing a perlite/sand earthbag  vault that i made a decade ago (i never plastered it and the sun ruined the poly bags)
Goal: build a shed where the vault is/was. In order to do that, 100cy of perlite/sand needs to get gone. Moving it will be such a bother that i would like to be making something new with it at the same time.

First thought: insulating base for cob pizza oven.  
i could just put concrete blocks in a circle and throw in/tamp the perlite/sand. Just build the base. I can worry about the oven build next year. Easy. But then i see rocket ovens look so much more efficient than just earth ovens. I really like the white option.
Would a rocket oven be improved by having an insulated perlite mass under it?  Or should i think of another use for my perlite/sand?
Any other ideas for what to do with perlite mixed with sand?