From my experience, the kids will be exhausted, yes, but they bounce back pretty quickly. When we have those kinds of trips my kids will either rest on the bus or they'll be singing karaoke with their group.

Those pit stops will also help a lot. If anything, it'll give them a chance to stretch their legs or buy some snacks.

Most importantly, they and the parents know it's not your fault. They know it'll be exhausting and crazy long, but it won't be you they'll be looking for answers from. They'll instead be seeing what you're doing to help make it all easier on them.