@Maya TorresLiterally the fist sentence of your post contains "I property manage" . 

First you say "no way something looking to invest in" yet you finish the sentence saying "to see if there's an opportunity or not."

New neighbor walks up 2nd sentence out of his mouth is that my dogs bark too much. 

If I say yes, which I'm leaning towards, would a written text for the above sentence cover me or should I add an addendum to the lease?

I read through our lease again and tenants are required to get permission/authorization to install items like this which tenants didn't; and there is a sentence in our lease that we are not liable for any issues with these additions.  

Your last sentence is the real problem. 

should be 'steam and hydronic heating' at the final sentence. voice to text failed me!

Now, re-read that last sentence.

And they'll read one sentence and form a complete and decisive opinion about a situation, as if all people that wear thumb rings and have tattoos are bad tenants.  

RE is indeed an outlier from your example, but in more ways than you implied.I think you are kinda missing the forest through the trees here man, especially cherry-picking that one sentence from my post.