When I had to leave my car for the 72 hrs, I arranged a deal with the owner directly (the day or night staff don't have authority to do this) at:
Super 8 Motel - Niagara Falls/Buffalo Area
7680 Niagara Falls Blvd
76 Street Niagara Falls Blvd
Niagara Falls, NY, 14304 US
Lots of parking in the back, well lit, security camera, but not the best part of town obviously.
$ 20.00 cash for 4 nights
The handy part about it is if you have to go back to canada in the meantime, there is the shopping shuttle nearby at fashion outlets.
The I-190 is only 2 minutes away and is a very quick drive up to Lewiston.