Oh yeah you’ll be fine just getting to something hard or hardish. I wouldn’t spend the $$$ on geotex or grid in that case either.
Have you ever tried to scrape the muck off yourself? Usually there’s a point where sloppy sticky mucky stuff stops peeling away, and instead of poop you’ll find hard ground. That’s what you’re looking for. Your excavator guy should know the drill and be familiar with whatever local soil type you’ve got, too.