Carsharing in open areas

Hello, Any precedents on how to integrate carsharing services such as Car2Go, Communauto or Zipcars that do not have specific restrictions on drop-off points? Our project is located in the area where you can just pick and drop a carshare wherever you want. I cannot define the walking distances to and from the parking location since it can be anywhere in on-street parking. The cars are equipped with permits to park anywhere in the city. Moreover, there is no guarantee to find a car but by experience there are always cars available in the area. Any cues on my next steps? Thank you very much for your help, William Gagnon