To this day, I still use the BiggerPockets Calculator for everything from 2-4 unit properties all the way up to the 224-unit portfolio we're working on closing this February.

Similarly, if you put several Class D tenants in a Class A 4-plex, what do you think will happen to the property?

Would like to become more savvy in the multi units properties realm separate from some of my commercial properties tenants who have excelled in that type real estate.   

The wrong tenant can lead to non-payment, evictions, and property damage.

Any recommendations on how many rental properties per LLC?

Hello All,
Just getting into the real estate world and looking to get better informed and learn from these forums
Stan

Are you local to the property?

Quote from @Brandon Croucier: Financing a commercial MF that runs as an STR is possible.Appraising a property based on the income is not, whos to say a buyer would STR the property. 

As others have said, the best thing your son can do is run far from this deal, buckle down, save his pennies (he probably already is doing this), house-hack, and improve a property with sweat, hard work, developing a DIY skillset, and self-managing tenants. 

Is it best to approach an architect or a land developer for what I am proposing?