That would be 60k down which isn't much more than the capital you have to bring now and you will shave off that PMI. 

In hard to insulate spaces, I have even used DIY spray foam kits.

And very often if you mention to each that you're also talking to another institution, they can shave a little off the rate.For the thing you did to remove collections, I'd check your report on all the bureaus as it's possible it was only removed from one and you may need to take additional action to remove it from the others.Note that for the bank or a mortgage broker to pull your credit, there's often a small fee, like $25-50.

Looks like closed cell foam is considered the best option.

That or spray foam (which personally sounds good but makes future work in that wall more difficult.

But then again, shaving a few bps off of commission on a $5M deal has a bit more of an impact.

Add a company that injects expanding foam under the foundation.

From a quick google search there are foams, chemicals, and augers to rid your sewer pipe of branches, debris, etc.

If there is access to underside of its floor and it's wood I would Try drilling and spraying a few cans of Great Stuff expanding foam thru the floor and see how that works. 

I saw 6 inches of missing water pipe fixed with newspaper and spray foam once (no pipe at all) .