Could you travel with your IL's? I know you've said they're great with the kids, maybe another couple of people as a distraction would help?

I'd probably feel like I should go and I'd drive it. But in saying that DD is a very good traveller so I don't know how I'd feel if she wasn't. When we do our long trips, we leave very early in the morning (like 4.30) so even if she does wake with the excitement, she falls asleep quick enough once we're travelling. Then we stop somewhere for breakfast and again for lunch. Would that be an option?

Or option 5? DH flies up for the day?