I find it it usually simplest to just be straight forward and express your concerns and see what the owner does.

Send him the 3-day pay or quit notice and a cover letter with the simplest comment:I will not tolerate late payments and will pursue all legal options available to me

I think the simplest, cheapest option for installing heat with the least maintenance issues - are baseboard electric heaters. 

That would probably be the simplest thing to do, since it's not likely you'd collect anything from her. 

Judgment is a key ingredient her though so in no way is a blanket treatment suitable for all companies.

The cheapest/simplest way I would recommend is using Excel spreadsheet.

This was an invaluable experience and a key ingredient to fast tracking our success.  

I proof-read everything (taking this to an extreme, I found a typo in the ingredients list on a bottle of laundry soap this past weekend).I will probably apply, but I'm curious if anyone has any experience with them.  

Numbers -You are missing one key ingredient...

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.