I spend majority of my time in central and North Jersey.  

I considered sound proofing the ceiling of the unit below but I’m reading articles saying that it can be very pricey and it won’t make a major difference.

I'm curious what the demand is for midterm rentals...outside of major metropolitan areas.  

Any major bank has this account.  

There are wholesalers in every major city in the country and they are buying at 70% to 90% of value all day long, every day of the week.

This cultural preference for renting creates a steady demand for rental properties, ensuring reliable cash flow for property owners.Additionally, many Germans face a significant shortage of affordable housing, particularly in major cities like Berlin, Munich, and Hamburg.

What happens if he has a major expense? 

I quickly learned that pools are expensive to maintain, but they’re also a major draw for guests.

Yes, it needs to be your primary residence and you can only have one primary residence (where you live the majority of the time, get your mail, pay taxes, sleep at night, etc.).

Inevitably there will be some "friction points" that you'll have to discuss/mediate, but ultimately if they are not willing to adopt a majority/all of your processes, then I think you mutually set up a date that works for them to move. e.g. 60 days, 90 days, etc...