The credit is treated just like money, even though the Fed doesn't print actual cash."

But you need to treat this like a professional agreement regardless of your relationship. 

Some note investors will treat a brand new note as a non-performer or close to it.

I would also have them treat your side of the duplex even if you don't see a bed bug.

You can't treat this as a little side job like mowing someones lawn.

Not needing seasoning is the rare exception, yet it's treated like needing it is.A blog post recently written entirely about BRRSRR didn't mention it. 

@Logan Splinter Thiele heating and cooling has treated me good.

Should we do this, or is there simply too much risk having transient room-tenants who won't treat this apt as their own "home" ?

Since a mobile home is chattel and not real estate, this transaction will probably be treated like the sale of a vehicle.

As always, you would want to talk with your personal CPA who has more intimate knowledge on your situation.One of the reasons you want to keep these two forms of investment separate is because of how the IRS is likely to treat either.