Definitely willing to rent one, they are less than $300 for the week. I'm assuming I'd need 2-3 days to get the muck removed from one end.

We don't have any neighbors, so we could dump that water into the same spot where the water overflows.

I was already considering aeration installation, to help keep the muck out when we go thru all this work to get the muck removed in the first place. I've read that an aerator would take years to remove muck from the bottom unless you introduced bacteria or something to help it along.