@Andrew Street are the AirBnB Host Groups you mentioned above found on the Airbnb platform or through facebook, etc.? 

Like you mentioned, there are lot fees that need to be paid monthly.

I would also note your mention of not wanting liability, but offering to "co-sign".

As you correctly mentioned, you’ll need at least two stays.2.

As mentioned the main downside to using a SDIRA to purchase properties is you get no tax benefit upside (depreciation) and have to pay taxes on UDFI.

No renting of any kind and explicitly mentioned even renting to others who live with you.

Those should drive a ton of traffic to your listing.Furnished Finder is the go to for MTRs (long term rentals with a shorter stay, over 30 days).You can also use FB like @Bruce Woodruff mentioned but you will need to get everything setup to take bookings.

Mention how the seller can close in days or months?

Not sure if this has been mentioned as I skimmed the last half of the posts.

You mentioned that you did your due diligence and that the people behind the project are legit.