I also read that a large fraction of tenants are on welfare and struggle to pay rent. 

Put a portion in the stock market via Vanguard Index funds, consider ETF's maybe through such sites as Betterment or others and put some fraction of it into RE.

There are old motels all across the country that can be repurposed into STR units, eco resorts, etc. with a fraction of the risk. 

In other words, if future appreciation is a "do or die" thing that is absolutely necessary for your financial success, then do not buy the property (unless the property is a tiny fraction of you overall net worth...Warren Buffet can afford to take a big 50% loss on a 500k house, but unless you have a huge stack of cash lying around, most beginning investors cannot afford to take a loss on a  property).  

Level of involvement (i.e. active management, passive, very passive such as fractional)3.

These are called fractionalized or multi-beneficiary loans.

I would be purchasing a fractional interest (I'd be buying a $100-200K piece of the whole).

Only a fraction make it to sale.So the answer to your question depends on your state foreclosure process and timelines, how often you go knocking, and what you're trying to accomplish.For example, if you are trying to buy these houses, you might need to visit them two or three times before you have any rapport. 

If so, all of it, or just a fraction?

Now if you’re using them for estate planning services that could be beneficial but most other stuff can be done for free or a fraction of the cost.