I did exactly what you described with wood 5x5 timbers. I wanted the shed door to open into a slope, which meant building up 5he low side with a timer wall. Drilled holes and pounded rear. I didn't want rabbits tunneling underneath it again. So a PVC shed on 3/4" crushed with fines.

Here is a post I made on jt a while back https://www.reddit.com/r/DIY/comments/kwri4b/shed_replacement_and_landscaping/