Best part is that it unfolds and if site prep is done, we can have a renter in in a matter of days upon delivery. 

I had not heard of the corporate housing by owner site.

I have done it with some contractors taking Paypal where you can use a credit card on that site with a fee, or QuickBooks is another one too.

There a number of good references on this site.

My work is mainly with investors and I co- host a women's investing in Allentown group.

YES, a person CAN sell without total site cleanup from a house fire.

I found what seemed to be a great property with a house for an STR and other space that I could expand for camping/RV sites and a barn that could be converted into a venue for events. 

(https://www.mynd.co)One of my co-workers at my last job (pre-covid times) used to work\invest with them, so I had probably registered on their site back then.

Besides registering with the city, are there any other steps required to setup as a STR/Airbnb host in Alexandria?

To set the scene: A cost seg study breaks your property into two important categories:1250 "real" property aka the building, foundation and other long life assets.1245 property aka anything that can be accelerated such as 5, 7, or 15 year property like carpets, cabinets, or other site improvements.