They are asking for 28% capital call proportional to investment amount. primary purpose of capital call to survive high interest rates for next 1 year and hoping interest rates gets favorable by then.

Here's the problem: They are not a sustainable asset for most to own; they are difficult and costly assets to exit through a sale; if you achieve favorable refinances, you may be able to use those funds to buy other (hopefully better assets) but are now faced with operating highly leveraged bad assets. 

I have 880 credit score, decent savings, and no other debt except for 300K mortgage on my primary residence (worth $1.5 million).

You need to have reserves in either cash or credit regardless of the situation. 20k can go away in a blink.

Once I get to a point that it is making enough per month that I feel comfortable taking money out of the business that would be when I get to the point that it is worth have a specialist assist me in all deductions, credits, and future items that will help me to transfer from a W2 to working for myself fully.

There are loan programs that will do a 20% down payment with a 680 or above credit score. 

When you tell them they will only get paid when the loan closes, they will disappear.If required, the only money you should ever send to the lender is for a credit check.

And, probably the biggest, the fee and waterfall structure are much more favorable to the GP when your investor base does not have many options.As for advice, the best is to view many deals and talk to many operators.  

You would want to look for an owner that has a loan through a bank or credit union or one that has no mortgage. 

Some appraisers are just going to choose comps on the less favorable side of the spectrum.