H's hesitation was meant as Last chance to be as a family and see how it goes. How H and I interact and if there is any chance or spark I guess.
Then it seems to me that he's open to that possibility. That's positive! He thinks there's the possibility that a spark might be there, that something positive can come out of it. Sounds like he's willing to try, if he's really encouraging you to go along.
What can you do to make the trip an opportunity for you to show the changes you've made? One thing I always have to tell myself is something I read (was it DR? Maybe it was something my DB coach said):
Is what I'm about to say going to bring us closer together or push us farther apart?
If you do go on the trip, H2H had some great advice for me (adapted for your sitch): Act as though you're with a friend. Have a great time. Forget about the R and the issues in it.
One thing that always Worked with my SO was when we were doing something out of the ordinary (museum, movie, a trip), I would just say out loud (which isn't entirely natural for me) as much as I could about what I was enjoying about it, what was great about it, how happy I was to be doing X, how great Y was, look at Z, isn't that cool... and the most amazing thing happened. SO brightened up like he was responsible for those things. It made him feel like a man, that he was taking care of me and making me happy.
And my therapist says that's what men want most in their Rs-- to make their partners happy and feel responsible for their happiness.
I'd go on the trip if I were you. Take advantage of your H's willingness to try.
