We have found that property damage is common and tends to be expensive.

Very common in old house markets. 

There is no shortage of REI meetups, just make sure you don't get tricked into listening to a sales pitch (which is common, do your research).  

But that seems to be a fairly common ploy among scammers to convince you they're legit. 

@Benjamin Branson - this is a common issue in South Florida.

In my area old houses are very common and just the standard investment.

If so, it should be fairly easy to pinpoint which costs increased and determine if the increases are reasonable.One common way for closing costs to increase is if the closing date changes.

If I was the seller and gave you access to all the common areas where things like galvanized piping, tuck pointing, and lentels could have been seen during that walk through.If there was limited or no access provided prior to offer being made, that is another scenario. 

Part of the scope of work mentions receiving data from the common platforms so they can verify host compliance.

I like your suggestions and will likely be reaching out to our tenants and having your payment structure (or something like it) in my back pocket if the need arises.