It just occurred to me and rarely anyone mentions them, if the ground you are trying to level is not dried clay hardpack/hardpan, the best tool for the job is to rent a power harrow.
The power harrow is pto driven and vertically mulches or stirs the ground rather than lifting it like a tiller/cultivator/disc does.
Or use it after tilling/disc/etc to break up the big chunks.
The other similar tool is a mulching flail but I rarely ever hear about anyone rent them out.
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