Wholesaling and fix and flipping are the most common, and these both require significant time, effort and money.Passive investing in rental properties still requires significant time, effort and money to acquire properties, as well as good credit and a good debt to income ratio to finance the properties. 

He’s cleans the common areas of the park like picks up litter, mowes the grass, etc. he lets me know if there are any violations.

@Saul Trejo, A very interesting and common dilemma. 

Primarily, authorizing expensive maintenance (roof repairs, walls, big stuff that exceeds the PM's authorization).You can make Limited POAs cheap (or even free) using something like www.legalzoom.com.

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

If you are buying properties that need rehab or that may need repairs from unseen deferred maintenance and you don’t have a reserve you could get into trouble quickly. 

You can also use this as a negotiation tool with the seller to show him the returns as the cap rate is a great tool but you need to forecast your levered IRR to see where the investment really turns out as the current cap rate does not show deferred maintenance /capex in most instances

Recertifications aren't very common any more.

You can advertise your vacancies, communicate with tenants, receive online payments, track maintenance requests, etc. 

But assuming your property is in Philadelphia, and the squatter does not have a lease, then your only option is Ejectment proceedings thru Common Pleas Court.