I know when you wholesale to an investor who pays cash that there can be no seasoning issues... but, if I were to negotiate with a FSBO to get a price $15,000 below FMV and then sell to an owner-occupants for $5-10k below FMV would there be any issues with their lender?

One thing I've done in the past is not take ownership of the property. Instead of recording the deed (which incurs a 1.5% transfer tax here), I get an option from the seller, a signed Warranty Deed (with no grantee), and a Special Power of Attorney. As far as they're concerned, they've sold it, and they move out.

I then record a mortgage for the amount of my "expected profit" to cover the option. I don't record the option, as I want the buyer's title company to see something they're used to: mortgages. As far as your buyer's lender is concerned, you are just another lien holder. Your seller is their borrower's seller. You'll get a payoff request and get paid from the proceeds at closing.

Since you have the PoA and a signed deed, it shouldn't be an issue. However, some title companies may not like the fact that the sellers aren't present. It's touchy, and you might want to talk to some local title companies about exactly how an absentee owner would sell a property. Around here, as long as the seller signs the deed in front of a notary, I can sign the rest with my PoA. In fact, here I can even sign the deed, but I don't like to go that far.