Then once I find a property that I like to buy I'll start looking at the comps in the area that have been rented and are currently on the market to be rented and make sure that my mortgage payment will at least break even with the rental comps.I'm using rough estimates on Zillow and websites alike.

How long did the renovation take, and how much do you estimate you would have made if you had chosen the wholesale route instead?

With that information, you can start to get good at estimating the rehab budget.  

For example, the estimated cash flow RTR shows is usually higher than what I calculate.How about the initial investment?

The next part is to get a contractor(s) in the door to give you estimates on rehabbing the rest of the place to get it to rent out.

recovering this negative position can consume years of the actual cash flow when using realistic expense estimates.  

The 6% vacancy rate is a good estimate, but local market fluctuations could affect rent.The HML terms (11.95% with 3 points) are high, so ensure a clear timeline for refinancing to minimize interest costs.

@Delroy WatsonI recommend connecting with @Jonathan Klemm to get an estimate.

I would also have a general contractor take a look at the damage and get an estimate from them.

Then track the date a maintenance issue was reported, description of the problem, who it was assigned to, when it's estimated to be completed, when it was completed, date/amount paid, etc.It doesn't have to be fancy.