Family is the most important institution.

Call around to your local banks and lending institutions.  

(I typically don't do take this route because I do a lot of work myself...which I cannot write off since I am not a general contractor).2) The financial institution will order a second appraisal.

He may institute a buyer fee of 30k for any new buyer in the association, prohibit rentals or require tenants / buyers approval by HOA.

Once there are some assets on deposit with that institution and you have a proven track record, there is much much more discretion regarding deals on their part.

It will be tough to last if you're depending on wholesalers, especially the institutional ones. 

The homes are used as an asset, alongside pension funds and endowments, to create quite a compelling investment for most institutional agents.

Within the same lending institution you're going to find varying qualities of loan officers in how they handle their business and how well they know their guidelines.

Does anyone have any recommendations for which lending institution is the best in Tulsa, Ok, for acquiring a conventional mortgage for a rental property?  

It can be subject to debt, seller financed debt, or new institutional debt.