You're right: the trouble is having to avoid legal obstacles, which almost certainly prevent you doing something like re-creating the one Cash Cab shot from earlier seasons of the show where Ben Bailey's cab is parked on Fulton Ferry Landing right in front of the Financial District.
Hopefully, someone will come along with a better answer and a better recommendation. In the meantime, you might want to consider, reconnoiter or visit the following spots:
• W Rd in Roosevelt Island
• Shore Blvd. in Astoria near the RFK and Hell Gate Bridges
• the Wagner College parking lots off Howard Ave. between Hillside Ave. and Signal Hill Rd.
If you can find a parking spot on W Rd., your only trouble then should be fences or railings between the skyline and your car.
If you can find a good clearing along Shore Blvd. with a clear view of Midtown Manhattan, you'll probably need to use special measures to get the shot right; Midtown will look rather distant in your photographs there, so you would probably need to position your camera far from you and your car and then have the camera zoom in on you. (So you'd need a camera with a decent zoom capability for this shot.)
As for Wagner College, there is a set of parking lots off Howard Ave. that overlooks Brooklyn. You almost certainly can't park there without some sort of pass, and perhaps not at all without an actual student parking tag; still, if you can park there then you might be able to get a good picture there.