I've found few tricks as simply as this that have as high of an ROI. 

But the trick is to find what works and what is not just sharks eating minnows.

Is this a trick question ?

Hoping for tips, tricks and insight on getting in at the ground level.

The other trick is when they do work it's tougher to hold them accountable to he quality/standard of work you want.

Obviously, not on that scale, and I'm not looking to screw my local municipality out of tax money (I honestly have no issue paying taxes), but what are some of these 'little known tricks & loopholes' that apparently only the rich know about. 

Those guys will know more of the tricks and nuances with hands on experience with local inspectors and their interpretations of the issues.  

The trick is marrying design and investment budgets together, which is incredibly difficult to do. 

We didn't have nearly the extreme issue as you, but we had a cat pee odor and used this and it did the trick. 

I had buildium for a short while and looked at others but QB has done the trick for us.