Return to LGA
From the AvWeb map it looks possible to proceed down the Harlem River Parkway and turn final to LGA at 1200-1300 or so.
It even looks like they might have to add drag to avoid overshooting.
Now what's the glide ratio when you drop the gear? What if that leaves you a bit short?
Rashly asuming that the gear comes down in time and does not drop you short, then you will need to ask the hydraulics for flap to steepen the glide and lower the landing speed.
Again what happens if adding flaps leaves you short? Retracting flaps generally incurs an immediate height loss (keeping in mind that in BA038 reducing the last increment of flaps got rid of a bunch of drag for not much loss of lift).
A successful landing at LGA or TEB, as many have already noted, requires crossing a precise point in space at a precise speed. A hundred yards or so short would likely lose all aboard.
On the Hudson, a mile plus or minus wouldn't have made much difference.