Will you need to ask them to leave?

So you now need more skin in the game with guarantees of the lease,rental increases,etc. as it affects a larger portion of the building now.No legal advice given. 

Either way you go have it resolved at closing, I just went through this on a house hack where one tenant had to leave for me to occupy and it took a lot of pressure off my end knowing that I don't have to handle that situation myself after closing.  

If you spent as much of your time on the Internet as I did you would realize that people today are taking advantage of doing things on-line is the typical way people do things without having to leave work or home. 

My wife and I let the issue go twice without issuing a fine) and had mentioned to him verbally in late April/ early May that notice is needed in the event of any changes and that he should review our condo docs.This leaves me with a conundrum.

I do own a small software business but I'm not really here to promote (especially since this isn't the place) so I'll leave those details out.

Back of the napkin math may work, but if I was the seller you do not have enough skin in the game to make it work.

I have done short term many times but obviously screen closely as they don’t have a lot invested and you want it near perfect when they leave.

One side is month to month and I was going to leave it as such because I hoped someone would buy it and live in one side and rent the other. 

That will leave that amount more each month for you to save and lead to more investments.