My estimates are produced on professional software, not the back of the bar napkin.

Regarding the 2% rule, that is more just a quick back of napkin calculation ... it should be more of a guideline than a hard rule.

The tenant would also be subject to all the other provisions of the lease, such as maintaining his or her residence in a sanitary manner.

You can draft a contract on a napkin and write it in crayon if you want...You can have an attorney draft the contract for you.

You could technically write a contract on the back of a napkin in as little words as you felt like writing.

They want you to purchase a home in move-in ready condition and one that is safe, structurally sound and sanitary.

If you do not feel comfortable with a "cocktail napkin" arrangement like I had then you should probably seek legal counsel to draw up something that will withstand the scrutiny of litigation. 

You could write a message on a napkin and if it hits the person at the right time- they call.

I've got a "sanitary" account, myself, for this purpose, at a bank that this is my ONLY account with so they can't start issuing "joint account statements."

I've estimated what that's going to cost and am putting the money aside right now for that expense.The "rules" of 10% for maintenance and 5-10% for CapEX are back-of-the-napkin stuff.