Those are concerns lenders have.

I am not sure I have seen any lenders ever offer any type of holiday incentive.

I know if I were to send an operating agreement to a lender that reads "LP member will receive return of their capital and 20% annualized return" they would not approve the loan.

Hindsight is 20/20.Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

I have a potential private lender, but I need to determine if this is a viable investment opportunity and explore the best financing options 

Find a good DSCR Broker that works with a variety of lenders so they can tailor your scenario to the right lender. 

Make sure that your lender will lend on them.

If you do not have those it will extremely hard to ever sell it to someone who will require bank/lender financing or refinance it down the road if you want to pull out cash on the ARV or future equity.The other rule of thumb is that you buy it New and that it was never on another property or location, simple built onsite or trailered in from warehouse. 

DSCR lenders are going to want to verify you are not living in the property when you start the refinance.

I also have a lender that has a loan product that will allow you to put $0 down on a home with an ADU that would add another rentable space to get income from.