This contractor has 0 reviews on yelp which I found a bit sketchy, but was able to vet him by his contractor's license, worker's comp, and by visiting some of his ongoing projects.

I use a CPA, too, but I like to do my own bookkeeping throughout the year and send him a tax package quarterly to review.  

Your account with hundreds/thousands of reviews is the biggest asset!  

The virtual agency, The Real Estate CPA, was featured on Bigger Pockets and has their own podcast but I have not found any reviews for them. 

Hi Rafael, I reviewed your listing as well.

Lets review some major points as they are pertinent to my advice.1.  

With Google, Yelp, Facebook reviews as well as what is on their site and what type of content they are posting on their social media pages....

So I get your hesitation to be too demanding and your desire for the problems to go away as fast as they can, however since you have NO property manager ( I don't use one either), it is incumbent that you take a more ACTIVE approach with management of your property.Let's review your situation.  1st time leak occurred, you sent a plumber over to find the problem.  

The local/ state etc (governing body) may not just "give you" one.

Maybe they've been burned by landlords in the past and are being very careful.You can legally reject them based on personality, facial tattoos, body odor, or other factors, but you better make sure you can prove that it wasn't based on any protected class like race, religion, familial status, etc.