There is also a big difference between condo rent and SFR rent in most areas, so I'm not sure where exactly you're looking but be sure you're comparing as accurately as possible.Los Angeles city rent control is different than the statewide rent control so that is something to consider, also there aren't a ton of reasons you want someone evicted if they are paying the rent and are abiding by the lease. 

But once my nephew and I got control of the property as possible buyers, I thought I could easily set up 3 RV's.

I would need proof of the lump sum payment at 18 years old and proof that she has control of the funds.  

Please find me two economists that agree on much of anything, except that rent control is generally bad. 

For my rent controlled tenants I must spell out the entire formula and cite the municipal code an then show the math.

Maybe look into Checkbook Control.

The ADU is not subject to Los Angeles Rent Control and for the first fifteen years of the ADU being built it is not subject to CA rent control.  

My credit coming out of college was bad, due to factors outside of my control, and now I am trying to get into real estate investing but I am not sure where I should be trying to get a loan.

You want to be able to control issues and learn the ropes while not having to drive far or having to count on third party management. 

There are things in the world you have no control over, tenants are one of those things.