Anyone with prior experience doing a seller-financing deal (MHP or commercial or really anything), please help!

Set very clear expectations, since they're living in the house with you think through how you expect the arrangement to work and make sure that's communicated to prospective tenants prior to move in.

We closed on 3/31 and made the mistake of not getting the seller out of the home prior to close.

Seems like I should continue to reach out but don't expect the deal I was getting prior.  

If you are purchasing a property with a lease you should also have a Tenant Estoppel letter prior to closing to review each tenants lease, deposits, etc. 

All I hear as an outsider (even prior to the virus) is that retail has been in trouble.

On paper, this is correct, but in reality there is a split driveway the leads to the back where the SFH is.Yes, I know, I should have confirmed the surveyors plans with the city prior to purchase.

But somehow there was a recording issue, and when the prior owner refi'd a pool of assets together, the original mortgage was not found. 

Tenant-1 told me in February that he quit his job (prior to the whole COVID-19 issue). 

A lot learned about using eviction aggressively when needed.The facts:Tenant wanted to leave, gives me '30 day' notice, then says they are leaving in 4 days, then moves out.Tenant wanted security deposit before they move out.Tenant has been model up to this point, communicating, handling turnover, cleaning, pays on time, etc.Police were called prior to my arrival by other tenant and they were told to put my property back.I show up on property unannounced and some of my property tenant knows is mine is still moved next to the door with their moving boxes.Tenant says to my face they were going to take my stuff in case I didn't give them their deposit back?!