If you're looking for properties less than 50 units, you'll have a lot of success with calling owners directly. 

Vacasa seems like they cover everything which is great for hands off owners, but they charge an arm and a leg.

@Shane Cordrey - Are you looking to primarily invest directly as an owner operator or have you also considered investing as a Passive Limited Partner in Multifamily ?

However, due to the whole area now being deemed by insurance companies as a "fire-risk" zone, I can't find a single insurance company to put a STR endorsement on a regular home owner policy up there.

Occasionally you can knock on the door and tenant will let you in, or maybe even the owner, but that is probably more rare.   

They should put the tenant on notice, and indicate their intent to terminate their lease if they don't correct the problem.If you have no such clause in your lease, you can find the owner of the property using tax records, then skip trace the owner and contact them to let them know of the situation.

I recently attended @Michael Ealy 's FREE seminar where you learned how to do all this and more without buying anything.I also attended a $2k course where I learned more in a weekend then my entire business school experience.A business owner I work for recently spent $20k on one of these scams.

Los Angeles make owners responsible for units to be free of vermin.

Also the new owner has the advantage of screening their own tenants and signing leases at or above market rents.

And it is very straightforward to file these, so I would expect it to be well within the scope of any operator sophisticated enough to pull off an owner financed deal.