Yes that's precisely how that works.

The cost of a new battery can be almost as much as the tool you bought is brand new.Miter Saw (great for molding and precise cuts)Battery Circular Saw (useful for flooring)Oscillating Saw (helpful for getting flooring under door jams and odd cuts)Shop-VacJig Saw (for flooring and intricate cuts)PencilsSpare blades for these tools, don't want to have to run out mid projectLots of white paintable caulk and a couple sponges for wiping excess off5 in 1 tool (cheap and great to have)Hand sanders, sometimes the electric/battery ones are too much for the jobStep stool (beats lugging around a ladder)Quality painting supplies like Wooster (sash brush, roller pads, roller and pole, plastic to protect the flooring)

No point of doing all the research, crunching the numbers, and getting it all down to an exact precise plan if she isnt even willing to even hear it out. 

Exact is the opposite of the goal...buy in growing areas and add enough value (force appreciation) where precision of execution, management, or valuation is not needed/relevant.

It could be good, but I'd project out the expenses more precisely.

Demiss, I'm not from your area so I can't offer any precise insight there but I do have a few pieces of advice that I've learned on the house hacking forums. 1.

Just be clear you have the right to kick them out over owing you to fix a toilet - when you have a security deposit that is there precisely for this kind of thing. 

Sure, cut the security deposit check - AFTER deducting any rent owed.The reason most landlord can't afford to forgive rent payments is precisely because they are not the size of a bank.And I disagree that this is a "relationship" business.  

there is a very precise way it needs to be calculated using the useful life left of the damaged item to calculate the amount you can withhold for example if carpet was damaged and the useful life of the carpet was 5 years and the carpet is 5 years old you cant charge them at all    To answer your question I would create a deposit accounting and describe in detail what you are charging for .  

I tell them I don't want anyone living in my properties that doesn't want to be there, and that is precisely what would happen if they signed a year lease and their situation changed.