This is one of the reasons that kids do better when parents live closer to each other. The kids will increasingly want to live their lives and be with their friends. Having to go away from that is tough. It is tough as a parent to deal with, but something you will have to learn how to deal with as a co-parent.
Remember that making it about your wants to have time with them will likely provoke a hostile S to push harder. Make it about what is good for the kids, and ask her how she thinks we can make this work for them by structuring this to their best interest within the reality of a joint custody situation.
If she thinks that joint custody is not good for them, tell her this isn't supported by the evidence based on your reading. I'll be glad to post the only good study of joint versus single custody w/ visitation if she doubts you.
Me: 50 W:43 S6, S3 M: 12 yrs. T: 17 M is bad & Not happy Bomb Mar '14 S 5 Feb '15 D Bomb 13 Apr '15 (but "no hurry") DB Coach May '15 Wants proceed on D Aug '15 Starting 1-on-1 negotiations Sept '15