"owned outright"- do the members have personal debt to support this, or is it both zero for personal and for the business?

From real estate investors to other small businesses, I talk to people daily who have no idea about the potential liability under the Telephone Consumer Protection Act ("TCPA")(47 U.S.C. 227 et seq.).There are two initial issues that can create huge problems with your suggestion.

My business partner has two STRs adjacent to ours that has several 1-bed units that rent very well during the week. 

Make sure you connect with the NHREIA, great group, they have monthly meetings in Manchester and a busy FB group with 3500+ members.

For maximum tax efficiency, consult a CPA to explore combining a partial gift and sale or structuring the transfer to reduce property taxes.

The business venture that went sideways?

I have experience with this business model. 

Having trusted resources in market have been helpful in managing our properties and contractors especially when my non-real estate related consulting business is in its busy season.

Are there many REITs that currently regularly engage in this type of feeder based structuring for a investors?

We're living in times when franchises go out of business overnight, but healthcare will never be since it is essential.