If you pull money out of your home, do you feel confident it will cash flow, or at least carry itself if rents fall 20%?

Assuming everything comes together and you are confident you can get the financing you then need to contract with a civil engineer and architect and or design build contractor to start the design and entitlement process. 

The owner of the home just let me know that he's decided to sell, and has given me the chance to make an offer before putting it on the market.I estimate that the market value is around $300k (fairly confident in this estimate bc a nearly identical comp nearby just sold for $307 with just a few small improvements).  

Since you have a demanding full time job and know experience, you'll most likely want to start off with turn key and then perhaps graduate to BRRRR as you develop more experience and confidence.

This whole experience made me lose confidence in AHP - looks to me like they are going down the tubes...

You will need to decide how much protection you are comfortable with in order to be able to move forward with your investments confidently.

When I bought my first park, I was pretty confident it was going to be just another version of an apartment complex. 

If your lender is willing to take you fully through underwriting before you're in contract, you can confidently consider removing the loan contingency. 

This will build your confidence for when you speak to actual buyers and sellers. 

Like most people do, I want the most desirable rates, but I also understand the importance of giving the investor the returns and confidence they need in return.