I am wondering if prefab or stick built would be the way to go.

Are you able to go there in person to build your network? 

Happy to go through some details on that if that'd be helpful.

You start by mentioning your age... you'd need everything to go just right for the rest of your life to make, best case, $400 or less additional each month net cash flow. 

And if so, are there any other ways to go about it for lexisnexis?

The low down payment house hack is the way to go.

I don't invest in section 8 housing and also have no desire to so maybe I am biased.- I live in Raleigh, 10-50 unit complexes will be hard to come by unless you're okay paying a premium.

I talked an experienced investor and he said $300 to $400 for San Francisco - the insurance company is going to go with the less expensive costs.

Second link is a similar size, albeit 10 year older home, in Setagaya Ward (a very desirable neighborhood), but still "only $1.2M. https://www.homes.co.jp/kodate...https://www.homes.co.jp/kodate...(2) Age. 

Most often it's in free & clear properties but, in a high enough desire area like these, and with low enough mortgage balance, yup, some can 100% get enough on the sale to have it all make sense because as @Jay Hinrichs has pointed out that in these areas the majority value is in the land not the structures on the land.