This is n spite of it costing much more than that to add an ADU. 

Hi Lisa, As an investor, I have worked with all types of realtors, but for investment property I would say that you have to have an experienced realtor in investment properties or you have to have enough experience for the deal to work with.Experienced Realtor will help you with the contract (which in many cases are not simple), but most importantly with spotting issues in the property that could cost you thousands.Your concern is valid so it is important to sign a Buyer Representation Agreement, in which case the realtor has to work for you over his/her own interest (or you can sue him).The idea is not to sue them, but to make sure you trust them enough to work with them. 

Have you reached out to the neighbors about sharing the cost of the repair?

It was very outdated but had no major renovation costs.

Quote from @Mica Moore: If you are not prepared, self management may cost you more than a good manager will charge.

The cost was the cost and the contractor let me chose to permit or not to permit. 

I have been advising friends and family against investing here due to high costs and no cashflow for years.

Villas and houses are also selling and renting exceptionally well.As you may be aware, the Tulum and PDC markets are dollarized, but many soft and hard costs are in Mexican pesos.

Cost of entry is lower as well. 

For example, the costs to obtain the mortgage are typically amortized over the life of the loan.Real estate also offers expenses that do not involve cash coming out of your pocket.