If you have a handshake/wink-wink kind of deal then you should get a Promissory note at least that outlines the terms of the loan and what happens if it default, who the loan is between, and usually in agreements like this the language is broad. 

This outlines things like guest/ overnight guest policy, cleanliness standards, roomie/tenant vs roomie/ landlord responsibilities...

You can outline this in the lease with clear examples so tenants understand how it works.

We told her it was her responsibility (as outlined in the lease agreement similar to what’s been posted).

In fact, a common colleague of Chris and mine worked with them for a few years but departed once he learned of the issues outlined above.   

Very helpful, think this is a great outline of the main steps one needs to take for MTR or even STR conversion! 

The two strategies you outlined are extremely helpful to consider..

The PadSplit fee is as Josh outlined. 

Your equity ownership is not voting shares/units.Will there be a summary accounting outlining the equity held by each investor?

Unfortunately, you may have a hard time enforcing anything about "guests" unless policy/procedures are outlined in your lease.