The property I've set my sights on is a 9-plex where the owners are willing to carry 70% of the loan at a 5.5% rate for a $1,800,000 building.

Hard money lenders specialize in providing short-term loans for real estate investments, typically with higher interest rates and shorter repayment terms than traditional mortgages.

If your plan is to sell/refi before the loan hits it's adjustment period, this seems like a no brainer (assuming there are no pre payment penalties). 

It was a huge selling point as there are a lot of folks that want a shop, or need a storage unit for their stuff and the cost is at least as much per month.I have a 7.5% interest rate loan on the rental.

@Gavin JexSo you want a bank loan and then seller finance as wellA bank would not be in second position so they as the owner / lender would be in second.Also 0% they would still be responsible for taxes on that at AFR so if your payment is $300/mo the loan would go off federal rates so they would essentially have to claim around $5k in interest income which would be ordinary income so they may end up paying all of your payment in taxes… just fyi if they did speak with someone on thisSounds like a steal if deal for you

Especially the program loans. literally the “seller paying commission” is just an accounting play to make banks finance commissions. 

Banks will not loan on properties inside an HOA if more than XX% are rentals.

But if caught claiming occupancy when you will not is a pretty serious offense: "Occupancy fraud is akin to banking fraud, where the lender can demand the loan be paid in full.

I would buy a lot, build a new home on a construction loan and then refinance it on a permanent loan when house was complete.

If it were me I'd be looking at taking advantage of a low down payment owner occupied loan and getting a house hack going in that market.