Hi, we did the section of the Erie Canal from Lockport to Rochester, during the last week of July. So just a small piece of what you'll do, and not sure that our experience fits with the rest of the canal.
Yes, you can camp at locks, but the availability of water and bathrooms was problematic for us on the stretch we did. In several towns, there were nice bathrooms and facilities, but they were locked up and you had to call a number to have someone come down to unlock it. We ended up using the fire station bathroom! So be prepared to make some calls if things are locked up.
It was also difficult to get food, because the canal path travels through industrial parts of towns, not residential and grocery store type places. So getting fueled up and watered up often required detouring through towns relying on Google.
We met some kind folks who let us camp in their backyard in Gasport, and when we couldn't find camping before Rochester we got a hotel in Rochester. As you get into Rochester, the trail is paved. that is when the tree root bumps start. Some nice person(s) spray-paint the bumps which does help, but sometimes there are so many you can't avoid them. But you are riding through dense, green, draping vegetation for miles. Very beautiful.
Overall, we weren't too impressed with the canal trail, because it was very hot, the trail was extremely dusty, water was hard to get, and a bunch of the trees had been cut down eliminating shade (that was a very interesting story, from the locals, of how that happened....
The history of the canal was incredible though.