Seneca State Park is where we left our truck and trailer... for 6 weeks while cruising the canal and down the Hudson to NYC. IIRC, we spent a couple nights in the marina when we first got there and they didn't charge anything additional for the extended parking time with the truck and trailer. No issue with leaving it there, and they took my phone number, just in case. Nice folks at the park office and in the marina. It was a good place to get provisioned, even though groceries and supplies are readily available all along the canal.
Best wishes,
Jim B.