Most of the smart locks on the market run off batteries, so no fear about a power outage (although the batteries could go dead, but most still use a regular key as a backup). 

As long as the batteries work you are good and don't need a key. 

Software will have built in automation for followups (for both PM & tenants), email, text, robo-call feature, accounting module, maintenance request & history, configuration of rent collection & due dates, amortization schedule, insurance, cashflow etc. 

I put this on the front and rear doors, so there is a "backup entry" in case a lock misbehaves (or battery fails).

These are NOT the mobile/manufactured homes you might be thinking of, but are *real* homes built in modules in a faculty and then transported to your site and put together on a foundation with all utilities already stubbed up.

Napoleon Hill, Dale Carnegie, Gitomer, Rich Dad/ Poor Dad, Cashflow Quadrant, Trump's "Think Big & Kick ***" and "Think Like a Billionaire"), I'm working on the Trump University's "Real Estate 101", and I've got "The Art of The Deal", "The Best Real Estate Advice I Ever Recieved, and Kiyosaki's "The Real Book of Real Estate", plus about a dozen more on their way from Amazon (Thanks to a bunch of loose change and the CoinStar machine offering no 8.9% fee by choosing an Amazon gift card rather than cash)I WAS going to check out one of the local AREIA meetings last night but clearly last night just wasn't the night for me (got out of work late, had directions on my blackberry and the battery died, then my car overheated in traffic...

Batteries last several years, but if you swap them out once a year you'll never go dead.

For example I always own two cars, thus a flat tire or dead battery (or even a motor blowing up) is an annoyance, not an emergency. 

It allows you to collect rent online, screen prospective tenants and manage your finances through their new accounting module. 

A battery, alternator, brakes and tires are much less than car payments.