I looked into paynear me and they are not accepting any small businesses at this time.

You shouldn't accept partial payments.

A conversation with the underwriter would be my next step to see what they would accept

With any of this, I'd talk to some local area investors and get a good agent behind you that can help with these things and advise you of the pros and cons of each.In some areas, I've heard of writing letters to the sellers, or even giving a acceptance type gift (like for real, other agents have told me in big markets that they will give the seller a non-refundable $25k upfront to accept (even if there's like an inspection issue or something!

Even if you get lucky with long term tenants who accept regular rent increases, you can't count on that when running the numbers.

I want to make it very clear that the real estate business, no matter which strategy you focus on, is difficult to get into, and you will be tested. 

We are still in the holding period but we have tested the market a few times to sell it and it is estimated that the home is valued at approximately $420,000 so there has been a lot of appreciation over the last 5 years.

Would it be considered acceptable or ridiculous to ask an accredited and very active RE investor who is interested in a deal you are looking at (whom you hope to develop a positive relationship with and or/ partner or invest with you) to sign a non-circumvention agreement, prior to them seeing the deal AND prior to having the deal in question under contract? 

If it intimidates you, don't worry, I will attempt to be concise and provide a laymens terms summary.Basic statistics crash course:Obtain as many sample rent data as possible (Zillow works)Define alpha for null hypothesis testing ( 0.05)Run multiple regression analysis (#bed, #bath, sq ft) against active rental list prices.Observe P-values for each metricResult:#Bed - 0.02#Bath - 0.04Sq ft - 0.02All are below or equal to 0.05, reject null hypothesis (statistically significant).Create multiple regression line using coefficients for each metric.Input variables from project property and solve for rent!

The scariest part of the house was I did not have all the cash available, I hustled my A** off to have the cash in the 30 days after my offer was accepted.