I believe it's an excellent strategy, but it won't work unless you have a desperate person trying to get out of a property, quickly, and they're willing to make the kind of money you need to get it done. 

You should tape that letter enclosed in an envelope with the tenant's name and personal & confidential underneath, which is excellent @Max James .In your jurisdiction change the verbiage to indicate that if they pay you before the 5th the late fee will not apply.

I believe in excellence and professionalism in everything that I do, pertaining to business and life.

@Bryan EXCELLENT!!!!

You've got some excellent advice all ready.

There are some excellent areas of the country that still do.  

I also figured out how to calculate it in excel if anyone is interested.

It's a great feeling to see someone else begin to excel after you've taught them what you know and they put it into action.

:-) You make excellent points, and as a matter of fact - as you may have derived from my first reply on this thread here - you and I are pretty much on the same page when it comes to how we look at the bigger picture of a business and with respect to "relationships".

California also has excellent net metering rules, which has to do with how much energy your system puts back into the grid over and above what you utilize.