This can be done by using sites like AirDNA, or by clicking on Airbnb/VRBO and seeing what similar properties are renting for and how booked they are at what rates. 

@Matt Rodak runs the site and I have met him a few times and had a number of discussions with him (more from the investor side not from the flipper side).

We can meet at any of my sites or yours.

Locally, I know an investor that runs a crazy profitable trailer park where he is probably pulling in a 20%+ annual return on his investment - but he has to self-manage because no one will touch it, collects rent and deals with evictions armed, and has several "overseers" living for free on site to make sure no one burns the park down.

This is in-line with the wise old real estate adage of “Marry the house, date the rate.”2.

Its a gamble to go the permit route or not in Philly and absolutely matters the neighborhood/your neighbors as they are usually the folks that will call L&I on you OR if your property is near other construction sites where inspectors would be traveling to/from. 

Provide four to five copies of drawings size 24"x 36" and 11 each Site Plan/ Boundary Survey.

Quote from @Tyson Thompson: Your best option is to use a data site like AirDNA. 

Yes this is very common in trading of NPLs with very aged past due dates, which could be outside of the statute of limitations. 

Another one site unseen, just signed power of attorney over for the closing at a notary off of Baker St!