It's not you being inhumane, it's you working towards your goal and offering a good faith solution after they have benefited from (what sounds like) lower than market rent during their residency.

I have both a primary and STR mortgage and I was thinking of using the STR HELOC to finance a new investment property.

I would be happy to connect and see where our goals could align. 

There are benefits to a well-run team that might come at a cost, but IMO your goal should be to learn as much as possible in the beginning. 

Our primary residence has a lot of equity, we have great W2 incomes, and >800 credit scores. 

Own 2 rentals(One condo in 92126 in @2009,One townhome in 92127 @2013 both properties are cash flow +ve ) and own a primary residence.

Here is the "lesson learned" : on the county listing, under "PARCEL#/NAME" is "Foster & Foster Tax Sale" (the primary law firm handles the sales) - scroll down the list,  if there is an addition firm listed (last time was AMS), there will be 2nd sale group. 

If the long term goal is to keep the property for future appreciation it could make sense to refi.

I’m no longer a fitness instructor and I’m full time running our Airbnb business and I know I can achieve my goal of being a millionaire by 35 yr. old.It wasn’t always easy and it certainly wasn’t “passive” but just like any business, you go through those pain points and obstacles to develop your product, systems and services so that you are able to create the lifestyle you want. 

I don't think your goal is achievable in Bentonville unless you start marketing or cold calling heavily.