For example, I hate to sell anything, but I am selling two properties to raise funds for a new primary that meets my goals.Study the market and really lock in what it will rent for.

They could self manage for several years, using the rental income, until the next phase of their retirement.If they have a decent amount of financial discipline, they may want to get a HELOC now before they build to get the most favorable rate.

It kind of depends on the type of properties you're looking for funding on.

WARNING: if you do not prepare for this, you can enter a death spiral: deteriorating properties lead to lower rents, worse tenants, more wear and tear, even less cash flow to fund repairs and ultimately erode asset value.I do not mean to rain on your parade, hopefully, this is a helpful long term perspective. 

Private lending using retirement funds is my personal favorite (I've done a few dozen loans like this) for the following reasons: passive, low risk, and high returns.

In this case, since they are borrowing their payments, these would get added to the principal balance each month, and interest would be calculated on that.If, for example, the interest rate on the note were 10%, they would implicitly be borrowing their payments at that rate.

What I recall from Aaron's deals was it wasn't about finding ever larger seller financed deals, but keeping the old seller as essentially a PML....keeping you from constantly looking for new funding when you already have someone that agreed to fund you essentially. 

You have numerous funding options so pick your poison.

Same goes for number of LLCs and what to fund them with, since bear in mind that CA tends to be more cumbersome and expensive to have LLCs than other states.California is generally more cumbersome than other states when it comes to taxes and filings.

Rates are high right now and I think you have a great situation here for you.