It's grandfathered in because it hasn't been redeveloped but this is where municipalities attempt to force redevelopment.

That being said, you should consult an attorney to help draft the terms you are attempting to construct.

I figured if I just purchased the property and put a mobile home on it, I could rent it out until the property was paid for and once I’ve got all of the note paid off on the home I would either continue to rent it until the market picked back up or just attempt to sell it and get out what I’ve out into it.

You should not attempt to deploy anywhere close to your max number.

They also stated the tax would be 40% of an estate over $60,000 but were unsure if that applied to the sales price, the capital gains or the market value so they're attempting to engage a CPA. 

Also, I bought 5 books recently from BP:BRRRR, both Tax books, Real Estate book, and how to get started with little to no money downWhat are your tips for starting up and attempting to use OPM or as little as possible?

Document all your attempts to offer partial payment or payment plans, it'll help with the hearing when it does come.

Just as you said, there should be no reason to not even attempt the higher rental rate if the current lease expires 5 months from now, especially when they're incentivized to do so with their 9%.

If so, tenants need to pay this portion.The second thing I would do is to advise the tenant that they violated the contract and ensure they understand that the pool needs to be removed when they vacate and the lawn needs to be restored (sod, not just a handful of grass seed strewn about) I would attempt to collect additional security deposit to cover expenses in case they don't do it.I agree that this is probably a sign they expect to be there for a while.

I recommend you doing this anyway before attempting any calculators so you actually know the "what" and "why" for the numbers.