Rocky, overgrown slope to pleasant, grassy knoll?

TL;DR – Best way to remove lots of varied growth and turn it to a lawn?

I've already done this once on the front-left of our yard (pic A – before, and pic B – after), but it was a struggle. After first trimming the growth back, it took a lot of time and muscle to remove all the rocks. Then I tilled, tilled again, covered the area with tarps for about 6 months to naturally kill anything left, and finally seeded. After a few years it still doesn't look great, but it is easy to maintain (pic C).

Now I'm trying to do the same on the front-right of our yard and am hoping for an easier, faster, better way.

Last fall, I finally tackled the right-front (pic D). I removed the growth and rocks and tilled (pic E). But, before I could get back to finish the job, lots of the growth returned (pic F).

Should I hand-pull all this growth and then till and then cover with a tarp? Is there any easier/faster way? Anything else I can do to prep the land and ensure a decent looking lawn? Any advice is appreciated.