I'm sure PQ'ers will chime in but I think you will be hard pressed to find 50a service. Make sure you bring your 50-30 reducer with you. WH might need to be run on Propane to help out.
It is a spectacular area - you will love it.
Cross at Peace bridge - Buff/Fort Erie - It's a lot better than Niagara falls. There is a KOA on Lundy's lane in the falls very close to the QEW you will be on from Fort Erie - plus a munch of other CG's nearby, but you have likely already found that! The Flying Saucer is pretty close - make SURE you go there for Breakfast
Enjoy!
Scott