Using a partner (experienced one0 for your first flip in this manner or any other similar approach of leveraging others experience, money, and knowledge is a great way to start. 

it is best if the current manager can reach our via phone/text/email/letter, however they communicate with the tenants about a week before you approach the tenants. 

She has a very creative think outside the box approach to help find what you want and submit offers that stand out.

Are there any spoken / unspoken rules I would need to know about approaching these lenders for these types of loan arrangements?

@Ellie Nasir Approach it from both sides of the coin.

@Alfred Koenig IIII'm not sure how you are approaching this. 

It'll be interesting once there's case law to see how we can approach that as landlords.Successful investing!

Initially I was thinking of approaching them with the idea of seller financing, but the bank between us would make it awkward.

If you're set on building on this land, it seems you may want to get pricing figured out in a more for sure approach (as you can, I realize material pricing right now is not 'normal') to get an idea of how much you really can afford to build.

Nothing but complaints about small items...some have been big, obviously, but just a very "adversarial" approach when it is totally uncalled for.