I've never responded to you before, or at least I don't think I have. However, I have some experience with this.
My H wanted to take the children to visit his family last Christmas. I assumed he would fly up to get them, and then take them back to Melb. No, he wanted to take 'our' car, which I had got in the separation. No asking mind you, just assuming that would be ok.
Anyway, I did let him take the children, as we have been quite mature and civilised throughout this mess. I did make one condition though. Someone had to be with him as he drove to and from here. It is fully a 2 day drive to Melb from here, and he was under so much stress, from work, from our situation, and the situation with OW. I didn't trust him not to fall asleep at the wheel, or not be concentrating.
I was sick the whole time, however, I knew that he would only have their best interests at heart. His mother drove to Melb with him, and then his father drove back up here with them.
One good thing did come out of it. He said he would never drive all that way with them again. Next time they would fly. Yayy.....
but didn't I suggest that???????
It was another case of Jo suggested it, so I won't do it...........
If you have any serious worries or concerns, re kidnapping, dangerous driving, and behavioural issues like toilet stops, then don't do it. The safety and welfare of the children must come first. It has to.
I hope you make the right decision, and that he respects that. Surely, you would think that they would put the children first, although I am seeing more and more that they don't. For whatever reasons they manufacture in their own minds.
I hope I have helped, in saying that sometimes it is OK to let them go out of state. However, I would never have let mine go if their safety was an issue.
hugs to you