Maybe the cashflow from the seller financing will be enough, but if it's not / or he's not willing to accept less than 20% on a down payment, I would love to have an alternative option to present where he keeps a piece of any upside. 

Alternatively, with a HELOC, I could buy smaller properties for cash and then use the BRRR strategy. 

This is probably my largest source of contention at the moment as to whether Id be better off going off with a cheaper duplex with less units, a bit less opportunity, but less repairs vs the alternative. 

I am looking at alternatives financing to Velocity Mortgage?

Though there is some risk of a negative review the only alternative really, is cancelling those listings and asking guests to rebook with the new listing.

My only alternative is hard money and the interest rates and fees are insane.

Alternatively, if you need to buy a home for yourself, there are more and more sellers open to seller financing scenarios too..

Alternatively, I would like to use the opportunity to strengthen the terms of the lease.

@Brian Gerlach,Yes there are similarities in terms that both are tax-deferred retirement plans, both can be self-directed allowing alternative investments.

You first drop the seeds (first mailer), then you frequently water it (repeated mailers or alternate contact), you provide sunshine (alternate exposure like online targeted ads to your target homes, or an ad in the local paper, etc).