I hear California LLCs have onerous costs but most states LLCs are cheap to maintain.  

But I also realize the macroeconomic environment - especially as it relates to interest rates - is very uncertain, and in 5-10 years time rates could be even higher than they are today.

I self manage my LTR’s and provided you maintain your properties, I get very few LTR rental calls.  

Your risk is going up fast as roofs wear out, apartments get out dated, AC units break and you've got no funds to maintain and improve things.

For example, as a "condo" unit owner, you may be responsible for maintaining the hot water heater or the carpet in your unit if it wears out or just needs to be replaced, but "not" responsible for insuring it if it burns up in a fire. 

This is to maintain sufficient temperature delta between return air and cooled air.

If she maintains the unit and is respectful of the premises I would go out of my way to accommodate her.

I imagine it would be a nightmare maintaining 100 different LLC’s and 100 different bank accounts when we reach 100 rental properties.

The impact of rent control on apartment owner net income  which would presumably necessitate an increase in property taxes on SFHs to maintain property tax revenue collections (assuming the city doesn't leave taxes on SFHs the same and instead increase them on a group that doesn't contribute to reelection campaigns).

If a storm comes and puts a branch through their roof it’s still their problem, unless the tree is unhealthy or dead, than you’re liable since you didn’t maintain the tree.