Canada overflight question

Hey all,
Anyone in the Great Lakes area familiar with the procedures for overflying
Canadian airspace? Specifically from the Detroit area to Niagara Falls, NY.
Is there a fee if you don't land in Canada? Do you still have to file a
DVFR flight plan? I can't believe you'd have to go through customs once in
NY, right?
I'd prefer to land in St. Catherines, ON , but I thought I read somewhere
that on entering Canada you have to land at first INTL airport, and I'm
assuming on return to the US I'd have to go through Niagara Falls anyway,
pay some landing/parking fee's and then play with customs, so not worth it
probably.
Flying direct saves me a few gallons, about 20mins, and avoids the whole
Cleveland Class B and curving around the south side of Lake Erie.
Any opinions?
Thanks, Chris