Need opinion for shed base...

I am tearing out my old shed. The concrete pad is 7 x10. I want to build a new 6 x 12 shed rotated 90 degrees on the old pad. In order to do this i need to build a 6x6 extension on the side of existing pad. Can i dig down, put a gravel base, lay down some pressure treated 4x4 so that they are flush height with the existing concrete pad, fill the 4x4 form with crush and frame my shed directly on the pressure treated 4x4's? Half my shed would have concrete floor and the other half would have a gravel floor. Is there an issue with this?

So, this base butted up against concrete pad. Frame shed directly to the pressure treated posts...issues?