Don’t approach the sales agent or person.

First qualified person that give a deposit gets the place. 

I have one LRT and one STR which are both under our personal names. 

Currently my hot tub maintenance person says I need to schedule her to come out to the property after every turnover to poor chemicals in and clean the tub.

Hi Nina.If I were not experienced in land lording and property manager, I would look personally to the extent you want to learn or experience property management versus hiring someone else that you trust to do the job.Yes, the cost for a property manager is important but not essential- the cost between property managers are not double or triple the cost of others (say like attorneys in some areas of law or cars). 

Our down payments came mostly from our personal savings and earnings.

I personally think networking is your best route.

If you decide to entertain this, due diligence will involve digging deep into the business financials to understand cashflow, solvency, and liquidity, his personal finances, and searching for any liens or UCCs in place. 

and include my tenant's name and this unknown person? 

Learning about the seller's approach and way of thinking can help you make your negotiation plan more effective.Every seller in the real estate market is different, just like every person is different.