The illegal in-law units/ADUs are somewhat common in the Bay Area - many people with paid off properties are collecting under the table rent money without reporting it to the IRS.

In hidden vaults beyond the veil,I guide investments without fail.With freedom to direct the way,My wealth grows stronger by the day.A private path few mortals see,What tool do I employ for me?"

The goal is to get off of the spreadsheet and move to a common sense, "what makes my life better?"

Also, as you highlighted the tenant base is highly reliable, with strong employment, security clearances etc.

I enjoyed the hard labor and comradery that I missed from my Navy days working in engineering.My question is, how do I go about getting more experience on paper without having to commit to an employer/contractor for a long-term position? 

I have a nice hi-rise condo unit and I get tons of companies asking if I do MTRs for Visiting Nurses, Tech Professionals, etc.My place is positioned near a number of large DC Metro Hospitals, but since covid work-from-home and recent lift of Eviction Moritorium, I have had few people with jobs, but a ton of people recently evicted looking to rent my place.The one viable group - visiting nurses has been excluded because my HOA will not allow short or mid-term rentals (anything less than one year is a No-No).They claim too many transient tenants cause excessive wear and tear on the property and too many people using resources like the gym, or pool or common areas.I think that's a lot of horse waste!

This can be really helpful if you're planning to scale up your portfolio or if traditional financing methods don't work due to self-employment or limited traditional income.Bridge Loans – If you're leaning towards flipping a property or doing major renovations, a bridge loan can give you short-term financing to get the property ready for sale or refinance.

Some people charge up to 4%. 3% is very common.

Software is a common question on BiggerPockets.

Here's are some other common terms for House Hacking -> Room Sharing, Owner-Occupied Rental.