I was able to get a private loan which I used to purchase the house then I used my own money to rehab the house.

I bought this property with a private interest free loan from a friend. the person i bought it from need cash fast so i offered them a low cash offer and they accepted.I had enough money saved up to rehab the house with my savings.

Awesome conversation! 

I have a private investor who will lend his own capital for ADU financing.

Or should I get a private mailbox in Oregon and use that?

to simplify, here's what i would do: don't borrow private money, or partner, until you have a track record. 

@Kaaren Hall after seeing your post i called them right away, their fees are extremely high for an HSA that for the most part most people don't have a lot of money in.I max my HSA every year, but if you have a self only plan you can only put about 4k /yr  and if you have some medical bills it's less.they are also very restrictive on taking money out, and no CC to pay the doctor. prior to speaking with them I was extremely excited to see this opportunity you suggested,  but after my conversation I'm no longer...I will look for other options now that I see there may be some, so thanks so much for bringing it up.

I’ve realized I need more passive options, and have moved to a syndication and private lending.

Again, this is a conversation to have with your accountant to ensure the benefits would outweigh the costs.Another misconception is that there is little value in a cost segregation study for properties that do not have a lot of personal property in them or very little interior build out, such as industrial warehouses.

Would love to keep this conversation going.