I do this !!! I send notes in crayon to get my point across.....it works!!
We have 2 association fees. One decided to save a few cents and sent out the bill in an envelope that can be turned into the return envelope.
I, of course, tear open the envelope and destroy any chance of this becoming a return envelope. It is the bill for the over 55 community maintenance. They are already dealing with folks in their 70's and 80's who don't want to do a puzzle to reconstruct an envelope.
I write a note on lined paper in crayon and large lettering. Of course I send my remittance in my own envelope along with my comment note. I'm almost sure I'm not the only one complaining.
The other maintenance for the entire Talega community tried the same thing last year and they got the crayon treatment too and are now enclosing return envelopes in their bills. It works!!