We started in the fall of 2013 and pretty much have all the same tenants from when each property was purchased (1 property the people moved out but then called to move back in but we had already rented to someone else).

I would be an out of state investor and i saw a nice property that i could likely rent as a 4 plex.

ASK, address and rent roll.

House is rented out regularly but also has a 2nd homesite that has a septic installed & perked for 2 Bed.

Buildium our property management software does not provide credit bureau reporting as service, despite request over many month from many of it's users.  It is suggested that  "Small" landlords use a collection agency,...

No.. depending on location, your property might have seen some nice appreciation.

We are located in the Central Coast of California, but are fine with anyone that has specific knowledge of California and could offer their services remotely.

My alternative would be living in a single family for a year and renting out. 

After paid off would bring in about 10-15K a month in rent and equity of 2 mil today's numbers (hopefully double in those 15 years).  4 rentals in texas 2 out of state.

I also converted my garage to an ADU (permitted) and is renting very well.