Also, the roof is asphalt shingle.

Some will say a "new roof" is just layering on a 3rd layer of asphalt shingles, with others it's a complete (real) roof replacement.

I'm a Civil Engineer and while my expertise is in pavements, I deal a lot with structural issues as well.  

If you don't have any reliable contractor networks, easy way to find someone is either A) go to the rental yard and ask who they know, B) call or go to your bulk/building material yards (gravel, topsoil, quarry, asphalt, concrete etc) and ask who they know.

You can't put a value on fixing a roof tile type when everyone has asphalt shingles.

Ask for references and then call those references.If we're talking about asphalt shingles there isn't much to it.

The same way investors and wholesalers do ... pound the pavement.

Terri Martin Start pounding the pavement and networking with realtors who are doing a decent volume of investment business.

I knew of a sinkhole in the famous PR-111 at San Sebastian that lasted years and years, they just put more asphalt layer after layer, year after year (like 20' or more of asphalt lol), and like 8-10 years ago, they finally constructed several concrete piers of about 60-80' and stabilized the whole thing making like a bridge.  

Yesterday was another 12 hour day of meetings and hitting the pavement.