There is no flat answer I can offer you here, because as you can see, it all depends on the unique economic facts and circumstances of the partners.

In parts of CA they have outlawed stays under 30 days and killed the VRBO market altogether.

CVS and Walgreens typically have flat rent in the primary terms of the leases which run 20 to 25 years at a time.As the years wind down on the primary term the amount down required tends to increase.

I've known a few people who paid a small flat rate and gave bonuses based on getting units filled (which is the most time consuming part IMO, showing and screening tenants) and they also gave similar bonuses when a tenant stayed and renewed a lease. 

I think it is 5 of them altogether....

I think we were quoted something like $2k for assembly (everything comes in flat-pack boxes like their furniture) and install. 

Are we talking renting for a couple months while she finds new place or are we talking renting with no intention of moving.First situation while not ideal might be acceptable for short term if that is what it takes to make deal happen.Second situation flat out sounds like a bad idea in my opinion.

The hardest one was a flat roof in Brooklyn.

I budget 5% for repairs on all properties, and a flat $200/month for Capex on single families or 7% for multifamilies.

This doesn't exactly answer your question, but have you considered offering a flat fee to a realtor to list it on the MLS for you with a note to contact owner for all questions and offers?