I know that chances are that the single mom tenant most likely won't be able to afford a drastic increase in rent and security deposit.  

hate you and think poorly of you because you're taking so much of their money-- even if you're providing them a beautiful and affordable place to live! 

What is my business, is if he can afford to pay rent.  

I think I'm priced out of single family homes anywhere decent, and seems like I can barely afford a 2 bedroom in Brickell.

Confirm they can afford the new rent rate, that they are not criminals, etc.2.

Well bad news a Conventional Owner occupied 2-4 unit is a 15%-25% down payment, even with a Conventional Affordable 2-4 unit the down payment is 15%.

I've yet to see how much mortgage we could prequalify for but we likely couldn't afford anything over $300,000. 

If you can afford the downpayment on a multifamily in San Diego, no matter what kind of loan, it's a great way to get into the rental market.

However, I'm curious if anyone has recommendations for timely, affordable, and investor-friendly contractors that are great with bathroom remodel, putting in counter tops / cabinets, and drywall patching / repair.

No, I cannot afford to do so for many reasons, including the following:Marketing - You cannot just post a listing on Craigs List and hope to find the right tenant.