For the estimating component, ClearEstimates is your best bet in my opinion, just remember to read and follow there set-up steps which includes downloading market pricing date (it's included for free just have to designate the exact market for it to get accurate cost data).

You would obviously want a rainy day fund for expenses, but if you buy 3 units and someone rips one completely apart, you're ruined, versus buying 10 and the rest can support you as you fix the others.Here's the other positive few consider. 

I am an expert in retail looking at over 1,000 properties a week so I know the space very well versus dabblers.

I bet that collections from the first through the sixth of March and April are materially closer than collections the first through the fifth.

Understand what your actual cost is versus the total cost of a property. 

One big difference that really attracted me to Puerto Vallarta versus other cities in Mexico is that the tourist zone and where normal every day people live is mixed.

Your best bet would be to get the borrower to modify the loan where you have a first which is the payments to the buyer and then you go in 2nd position with the balloon.

I can't imagine a landlord, in these circumstances, would be unreasonable with a tenant who is facing hardship and risk losing out on cash flow versus working something out.  

Unfortunately, if you do not think that you can re-rent the unit right now, your best bet might be to just take that half-month rent payment and deduct the remaining from the security deposit, or go after them in small claims court once the virus blows over.Best of luck!

Approach the agent and seeing if they will agree to a lower fee may be your best bet in this case.