It is a protected class in several states...

Seller should record their lien against the property, you both should have an attorney review to make sure all interests are property documented and protected, and i think everyone is in a good place. as far as evicting tenants... this is up to what you and the seller can negotiate. i would still be putting on the same contingencies - appraisal, inspection... know what you're buying. don't get blinded by the seller-finance piece. 

As long as we keep any of the protected classes out of the discussion, is it ok?

They know the law inside-out and protect you from bad renters or unique situations like the COVID eviction moratorium. 

I email all my documents as pdfs with password protection, then I text the passwords to the person receiving them. 

There are ways to mitigate the costs and protect yourself to the extent possible.

If you haven’t done so already, consider protecting these assets under a legal structure, such as an LLC or trust, to ensure they are secure.

@Kwanza P.Here you can learn more about non-recourse loans:https://www.biggerpockets.com/member-blogs/2810/46115-real-e...Here is a list of lenders offering non-recourse financing to Solo 401k:https://www.biggerpockets.com/member-blogs/2810/50272-list-o...You protect your property by purchasing insurance. 

This FLA build new rentals got WAAAY over sold and huge FOMO that got buyers to lose their wits about how to protect their money..

Two policies might be the right move to protect both interests.