I had put 4% interest rate, because the turnkey company was offering a deal for rate buy-down upto 4%, which was paid by the builder.

@Mateo Dabila, if you have $10k in cover-able closing costs to apply that much seller assist to, you could take 6% seller assist on a conventional loan if you put 10% down.

Motivation is to overcome down payment hurdle for expensive houses for STR

If you are trying to convert a property under and hoa into an str, your job gets even more complicated as the HOA itself may have its own regulations IF it even accepts it at all.caution: STR market is over saturated in these parts and some of them are shuting down and being converted into corporate housing, mid term rentals, or furnished long term rentals.

This way you do not have to refinance as soon to recoup your initial capital.I mention a 60/40 split because rates usually do not get any better if you put 50% down versus 40% so it might make sense to save a little.

roughly a $40k investment i was hoping to kick down the road.

TONS of SFR listings in the Troost corridor heading up to the river and then curving East along independence Ave.But they present many challenges; vacancies  (due to below C market tenant pool), increased maintenance and repair costs (due to below C market), and increased cap ex due to homes in this particular region being older (many century homes).Then, even if at the end of the year it does well from a financial analysis standpoint, you may struggle to find the necessary and diligent and high performing property mgmt necessary to manage said property…so then if you self manage OOS, you will need a strong ‘boots on the ground’ team.many challenges come with these ‘$ sexy’ properties.

A bank can issue a loan specifically to "bridge" your down payment for your next property before you sell your own property. 

Will see how it's shapes up for due to some other constraints like angle of stairs coming down and movement of drain pipes.

Federal Regulators HATE smaller real estate investors for some reason and really come down hard on banks for funding their deals.