The other route is to have it professionally remediated so that your family will have a mold certificate stating that it has been done professionally.

It could not be remedied within 60 days.  

Also have them quote architectural shingles, not cheaper 3-tab.If money is tight, engage with a local storm remediation firm who can likely get the replacement paid through your insurance as long as a decent hail or wind storm occurred during your coverage period.

Misaligned fences are very common and most buyers close without requiring sellers to remedy prior to settlement.

Then turn around and sell it to this developer.Downside is that if there turns out to be serious issues and the developer backs out, you could be stuck with the remediation and back taxes.  

I would start with a 20min conversation to get the basics figured out as to how they might remedy the situation.- Buying their place would be great but sounds like that isnt an option- Maybe there is something the neighbors want, in return for not calling the police.

It was a former gas station in the center of a new and booming arts district, but even if they did the owners liability was 10k with the likely possibility of a windfall in the form of remediation management (sort of like insurance in the event of worst case).

These are not the only remedies the Landlord has if the Tenant violates or breaks this lease.

I have had situations where my attorney has had to charge me big fees on the buy because of title issues etc. that I can't pass on to my buyer.I've also had issues with the property come up with my buyers inspection that I had to remedy and couldn't recover from my buyer. 

Ask nicely the first time but include a deadline for them to remedy the violation.