I built a gravel foundation for an 8x14' prebuilt wooden shed. I spent a lot of time addressing drainage and most aspects of the foundation. Now it is finished, I think, but I want more experienced opinions on leveling it.
Here is the shed foundation nearly finished with rough leveling and compacting:
The core of the pad is mostly crusher run which my local quarry had as more sand than stone, meaning it compacted well but may not drain as well. The perimeter has a french drain-style trench filled with #2 stone and much less sand, so drainage should be okay.
The way I leveled it is using a long 1"x8' board and a 2' level. I roughly leveled the subsoil to have a slight grade for drainage, tamped it. Roughly leveled a central 4"-deep pad of crusher run with a slight consistent grade for drainage, tamped it. Then more carefully did iterations of filling edges with #2 stone and topping it all off with another few inches of crusher run. I raked, scraped, tamped, leveled using the board, and repeated, aiming for a completely level surface. Board and level shown below:
I am asking about how to check if it is good enough now. I put the board down with the level in the middle of it, and I checked level in 9 location with the board east-west (16+ft length) and another set of spots north-south (8ft length). In each location the bubble is either balanced, or has only a slight dip on either side (I can pick the low side up 1 inch or less and get the bubble balanced).
I figure the bubble does not need to be perfectly balanced everywhere, it is good enough to be mostly balanced or within an inch of balance in all locations. My reasoning is that the shed will sit on long skids thus distributing its weight and 'averaging out' the slight (0-2 inch max) dips or rises that might remain over the whole area. Also, even if I got it perfectly level at this point, settling may not be perfectly even, so level within an inch seems good.
Is this foundation level enough to receive a shed? If not, what steps should be taken to get it even more level, or what measurements should be made to ensure it is good enough?
The shed will be used for garden tools, as a workshop, and as a small weekend cabin. Most buildings I've lived in are not perfectly level, so being slightly off doesn't seem too troubling to me, but I also have never built or worked in such a small building.