Take a semi-retirement and get a gig that is a more chill when you come back. 

Lots of good secondary / semi-tertiary markets in the state that might have some good starter investments - maybe some low cost BRRRRs?

For example in the Reno, NV area there has been a big push for diversification beyond hospitality and now Tesla is building battery packs and the new Semi Truck.

Don big difference in production building in the South /  compared to semi custom in other areas..

Also we are building semi custom with very good subs so its not like the cheapo starter build to rent homes that are slapped together our houses are in great shape day one.. but there is always some cosmetics or something does not work right and OEM fix's it or the sub fix's it.. no big deal.

So my question is, where can I find analysis tools or spreadsheets that I can use to work out the numbers and put together a formal/semi-official/convincing package to present to the prospective investors?  

I used Semi Gloss . ( yes it shined for the first couple years , but it lasted 12 years until I decided to put on Vinyl to match the house 

Semi-annual?

Do I need permits if I bring in a mobile home or similar semi mobile structure?

not semi passive option OP is seeking.