I am confident that I will be able to refinance the remaining seller note principle with private money to allow me to hold off on putting more money in the deal.

You don't need to know everything to get started; you need a foundation to build on, and the rest will come through experience and then refining your education.You can build a basic understanding of investing in 3-6 months.

Start by building a solid team, analyzing deals carefully, and making your first purchase to test and refine your strategy.Good luck!

@Zongfu LiWhere are you trying to refinance (what state?)

I want the next value add to be an ADU addition, but the appraisals are undervaluing the ADUs so refinance to extract capital seems unlikely. 

Always happy to swap ideas and keep refining this process.

If you feel ambitious, you could try a BRRR strategy adding additional equity to the subject home and then taking equity out of it to pay off either the HELOC or if you decided to the refinance the primary residence. 

These loans are short-term as you mentioned, typically 12 months, so you'll need to refinance before that balloon comes due.

Without having a credit score you can expect to have a 10% reduction on the LTV or loan amount towards a purchase or refinance.

Something to consider to is that if you are able to refinance after the addition and pull out some or all of your new investment and the cashflow still makes sense then by all means I think go for it.