Once the leak is detected and repaired, send the tenant a coy of the invoice so she can go down to Huntsville Utilities and have her bill adjusted to account for the leak.  

If all items are completed then we invoice the full amount agreed upon.

Does your house cleaner normally give you an invoice after every clean?

Provide copies of emails, phone call records, text messages, lease agreements, Property Management agreements, invoices, or whatever evidence you can provide to bolster your case from the very beginning.

@Tucker Kincaid Wave Apps has a great free version to use for accounting and invoicing.

So my first question is this: I'm using QB Self-Employed for our personal finances, would it be a good idea to simply invoice each business for my time that month?

Pay them as soon as you get their invoice and treat them like gold

Enter a maintenance request, assign a vendor, attach a fake invoice.

The renter pays you after you provide them the invoice. 

Enter a maintenance request, assign a vendor, attach a fake invoice.