She is renting the apartment, not the entire property.It's very important for landlords to understand Landlord-Tenant rights and maintain control of the property.

Do you think purchasing a property in Philadelphia, PA, and managing it remotely from Westchester, NY (Roughly 2-2.5 hours away) with the help of a local handyman would be too much of a stretch?

Quote from @Henry Clark: @Michael PlaksIf they want to stop money laundering and funding terrorism they can control the border.  

For certain areas annual pest control may be needed for colder areas maybe you run the risk of freezing pipes.

It’s a balancing act of controlling costs while also controlling risk of personal injury to your tenants and property visitors as well as maintaining goodwill with all involved at the properties. 

In the event of an acquisition your "Checkbook Control" set up would not change.

Since you're a citizen but you live and work abroad you'd still qualify mostly for second homes occupancy or investor non owner occupancy (primary is hard to claim if your job requires you to be physically next to the office as an example so an underwriter isnt going to readily believe you unless you can get HR to write you a letter to state you're remotely capable of earning this income/job duties anywhere).Hopefully that helps let me know if you have further questions into mortgage planning.

Bigger Pockets is a great place to find a real estate tax accountant.A good real estate accountant can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding an accountant who specializes in real estate taxation, business taxation, financial planning and tax planning.You may want to consider working with your accountant remotely to expand your options.I would also recommend looking for a accountant willing to work with you throughout the year.

It sound like you have your area under control. 

Of course you can never have control of the money and you must have your QI in parcel before your sale completes. .