Is my foundation design for this garbage can hutch overcomplicated?

I am looking for feedback on the plan for a hutch I want to build for my garbage cans and table saw. I plan to have it sit on a slope next to my driveway. I’ve used a deck planning tool to guess at what size all of the lumber should be but expect I am making a bunch of amateur mistakes.

Here’s some photos of the site:

The fence is where I’d like the hutch to sit flush to. I’ll be tearing it out.

Here’s a mockup of kind of roughly the idea:

(I ran into some surprises with how I’ll have to deal with the roof so I left the wall outline unfinished, but you get the idea).

Here’s a few pics of what I think the foundation will look like:

I didn’t draw it in but I plan to have all the posts in concrete. Dims are approx 6 ft wide at the widest point, 4.5 ft tall (once framed) and approx 9 ft long.

(Album with all pics)

The beams are 2×10, and I think it’s OK to use 2×4 for the joists since they’re spanning less than 5 ft 8”. I was planning on using strong ties for all the connections (post to beam, joist to beam).

Is there an easier way to do the end that sits flush with the ground? Right now the plan would mean I have to dig down quite a bit to make room both for the beam and the posts. Is there another way I should be doing this that requires less digging?