will not abate the smell of stale urine which will have seeped into your flooring. and last long after the tenant has left.You have held yourself out as a pet friendly landlord and your tenant is trying to do you a solid.This is your asset that is about to become damaged.

A JV contract would stay in each parties possession, but in the event of a disagreement, you may end up in a civil court battle with no way to cloud the title until the judge made a ruling. 

Additionally, if you have major development/reuse/rezoning plans, find a lawyer who works real estate in whatever area you are in and have them connect you with the right people to have the conversations to insure you aren't buying into a battle with the city/township.

My first step would be to refuse those two requests and offer to let him out of the lease "no harm, no foul", if he is not happy with the arrangement.  

What I did learn within the last few hours:Owner run a real estate organizationrecent deals from this organization (property purchases) run a high of $2Million (so I'm going to be battle a Goliath)I am currently researching the property to see how it is currently zoned.

Trust me, I know it's very possible and I know that's the main battle in this game.

If its already on the MLS, you are fighting an uphill battle.

That which we call a rose, by any other word, would smell as sweet".

But if you are already questioning this line of attack then a tenant will smell it.When someone is paying less than $600 rent a $100 increase seems like huge, but again if you are far below market then you should welcome them moving on.

Unfortunately you lost the first battle and the neighbour now believes they own you, and rightly so, they do own you.