I remember when I got out of college and started with a bank, my learning curve was steep and I made a lot of mistakes.

Since you are living there, it should be much easier to set up showings rather than a traditional rental traveling to the property.The biggest mistake I have made, and seen other makes, is loosening their guidelines after a few weeks/months of vacancy because they have simply had enough. 

I had no help what's so ever but I learned from my past mistakes and Ill try again and get more info.

You can hear real-world examples of how others have built their investment portfolio and (hopefully) learn to avoid their mistakes.4.

Learn from their mistake. 

That was that, probably a mistake, but it worked out so far in the sense of having the home rented and a good paying tenant. 

I'm trying to understand if he made a mistake or if the DOT is being un-reasonable.

You've got to learn from your mistakes.

All of my clients that came to me after they purchased an aircraft; I have spent years and tens of thousands of dollars trying to correct their mistakes in purchasing.

One mistake I did make, was my building was not in an LLC yet when I hired him to do the work, so I think I may have personally liability should things take a turn that direction.