The properties are trashed, and not worth much. 

Definitely worth looking into!

Most other things are worth attempting to resolve yourself after ensuring safety and doing research.

(You say it’s worth about $100k more than you’re paying so figure an extra $15k.)Maybe you’d be better off partnering with the parents unless they have zero interest?

The 2-3% points in extra cost are worth it if you plan on using as I described above because the use would be for a few  months at most and due to that short term use you can survive a rate adjustment up.But, if you have no plan to payoff the debt like when using for a down payment on a long term hold why pay the extra cost for flexibility and have the additional risk of the adjustable rate with the amortization looming when you can get a fixed rate second mortgage. 

Most land bank properties, Detroit or Wayne County, are trainwrecks and cost more to rehab than they are worth - unless the market keeps improving.Be careful on the next one, but keep improving Detroit!

You don’t need to be someone that owns $100M worth of real estate unless that’s really your goal. 

A STR is a completely different animal in my opinion, in that it requires more work and much more compromise, but financially is worth the effort. 

I won't pay more than what it's worth to me, regardless of what someone else paid for it.

But the location is great, and the layout could work for a flip or a rental with multiple units.Would you take this on, or does it seem like more hassle than it’s worth?