If you use an online mortgage payoff calculator with $280,000 at 4.8% for 29 more years, paying $2000 extra principal per month, which is less than the $30K extra you say you'll pay annually with your line of credit, says your mortgage will be shortened by 21 years and save you approx $178,700. 

Is there a good option for tenants to pay online without me setting up my own website?

I did none of it online as Zillow is a joke when it comes to rental rates in my area.

I have access to the full deed database online in my county. 

I'm looking to start going to a few options and luckily my state has all deeds, liens, etc listed online. 

To bear on the safe side and protect your investment, I would recommend Yes.

What safe guards do I need to put in place for buying outside California.  

I am not suggesting this is the only issue but I have seen some listings in the area with horrible photos online which usually is the first impression.

These are safe investments for the most part. 

(I know that no one wants or plans to get audited but better safe than sorry)  I haven't spent any time with Google Drive but I will explore it as an option.