I have researched the top brokerages in major metropolitan areas, and I'm reaching out to them Via email and phone calls.

Any major pros/cons for the ones listed?

All are within 30 minutes of major employers.  2) Like most metro areas in the surrounding states and regions, we've had an inventory shortage for more than 5 years.

Also the Adelson family of Las Vegas Sands fame have purchased a couple of big parcels with hopes to build a giant casino/convention resort perhaps anchored by the arena for the Mavericks for which they also just purchased majority ownership from Mark Cuban. 

Even my seasoned and great landlords are going to have major issues with this.

I suspect this would happen if various parties were given the ability to ask questions in nearly every application for what this thread touches on - and I have major concerns about integrity (and credibility) issues involved in putting yourself in a position to defend this position if ever challenged. 

fix and flips are the vast majority of the targets for private lenders.

Also the majority of those costs to covnert to a 2nd unit will need to be capitalized and depreciated, but some things (new appliances, flooring, paint, kitchen cabinets) can be shorter year assets vs. across the full 27.5 and IF it turns out that unit is > 50% you can use bonus as well on those items.

It does feel like there is likely a major market correction coming, but due to limited inventory of vacation-rentable units in Maui I feel like I should be somewhat more protected from the effects of said recession.

And he can purchase the property himself from the defaulting borrower, or purchase a (majority) ownership in the subject property.