If you can train your tenants to change the filter every month, then more power to you........But in the vast majority of situations, that menial task is rarely done by most tenants.....kind of like having your dentist tell you to floss every day :) Some do it, but most wont...at least not on any regular basis for a sustained time.Must be different in CA....or my house...I change the filter every 6-12 months and its is barely dirty.

He typically contains himself to his apartment, but he has a window that faces a handful of other doors/court yard, so I myself have been threatened through the window and I see other tenants running to their doors when we can hear him screaming from our parking area.

Both a and b are addressed by inspecting the unit. 

There are some 20 of us here, working with clients remotely, no need for a face-to-face.

Most of us are facing the same challenge-finding cash closing properties.

Please don't underestimate the importance of the face making the offer.

Our days can be long, we are perpetually faced with new challenges, sometimes it feels like I'm the only one witnessing the insane lengths people will go to just to deceive or mislead for personal gain...these are just a microscopic parts of life we all must face and manage on a daily basis.  

I would rather not be the face of the next big county government scandal, even though I'm one of the aggrieved not the one responsible for causing the issue.

Additionally, if you prefer a face to face I know an Excellent CPA in the LA area who works with a lot of investors.Good luck in your search! 

HOWEVER, that opens up a can of worms re: RVs as permanent residences - it's common that RVs are not permitted to be used as residences on bare land except under certain circumstances (such as during active construction of a primary residence); usually it's required that there's already a permanent structure on the property and the RV (or other small building) be considered an "accessory dwelling unit".