It was an evolutionary process for me and is can still change a little as I change or the markets alter.

What does the lease say about additions/alterations to the property?

You do not alter the property, move things around, tailor it to their specifications - because it's NOT their property. 

Can you paste your repairs and alterations clause here...I need to write into the contract to protect myself from future tenants hiring inspectors or professionals to do stupid tests.How should I beef up my current repairs/alterations clause ....

Basically, I wrote it, then we discussed together and altered it to make it more agreeable to my husband, who wasn't as interested in moving forward, so it was much more conservative.  

Can't speak for the others from first hand research.Rules vary in terms of the threshold for eligibility, eg: >2 or >3 units, rate of growth allowed each year, rate at which capital expenditures can be translated into increases.

There should be something in your lease that says that the tenant is not allowed to make alterations to the property.

I also sold 6 homes (selling 1 more this month).In 2018, I made a dramatic change to STR (short term furnished rentals) via Airbnb (and VRBO) and it has altered my real estate investing dramatically.   

Love Derrick E's take on his approach directly working with 'listing' agents and not needing anyone to negotiate or translate (or get in the middle) for him. 

But figured someone in this forum could translate it for my current situation.