I'm also not that mechanically inclined.I'm not so keen on solution 2-4 as it would require intervention from the tenant to cleanup and replace used up portions, and I'd really like the tenant to not have to think or worry about placing or emptying stuff.  

Now I'm looking to get out of my present line of work (mechanical design), and build a company to include different aspects of real estate.

Any experience with common brands and which have a strong locking mechanism? 

Think of a mechanic that is telling you to buy Car Model A over Car Model B... they are the ones in a position to know that Car Model B breaks down all the time, based on what they see rolling (or being towed) into their shop. 

There’s a big difference between self managing your rental (finding tenants, background checks, leases, collecting rent, coordinating issues, etc.) and fixing the mechanical problems that come up.

Check when the roof was replaced and the age of the mechanicals too.Good Luck!

We did our upgrades incrementally,  with emphasis on the common area upgrades/landscaping plus repairing/replacing broken appliances. 

You need an electrical and mechanical inspection for installation of AC even if you have a furnace and the ductwork in place already.

I am currently a fifth year (5/5) Mechanical Engineering student at Drexel University in Philadelphia, PA, I have recently accepted a full time job offer as a Mechanical Engineer at a chemical company located in Deer Park, TX with a start date in July 2019. 

@David Brown Has the seller already agreed to owner financing and you are wondering about the mechanics?