Be careful with Phoenix... it was a hot market for a few years and it really tanked out for positive cash flow.

How does one acurately assess the value of self storage business?

If I'm down there and see a property I love, I would probably still buy it, with a regular mortgage.I do have to figure out where I want to live mostly, but some of that will depend on what I can do with the money and how confident I feel about longer term stability.Renting out a Spanish property while I'm in Canada seems somewhat easy, as it's pretty common there to rent out fully furnished places, and tourism rentals would be an option too, to help pay for it.Canada on the other hand, I'd have to put everything in storage or sell it off every time I want to be away and rent the house...

I currently have 5 rental properties that are all single family residences and look forward to expanding my portfolio to contain more income properties like storage sheds, RV parks and commercial properties. 

Is there a good book that describes how to invest in self-storage?

A full tank in a year is way overuse/abuse. 

The property is 1.5 acres with the 5 unit apartment and a 4,400 sq ft building that could be storage facility. 

Dishwashers can be problematic, since there can be water in the drain area and they are pretty much plastic pipes.If water was drained from all supply lines and the water heater and toilet tanks, then you only have drain lines to worry about.  

As I was running electrical for the new storage units I was building down there I found 2 "Cherry" magazines circa 1982.

Basement flooded, HW tank was floating & horizontal & the electric panel was about to short out.