Here if the non-custodial parent took it back to court they would be risking the court determining that amount of travel is not in the best interest of the child and moving the parenting plan to a long distance plan (no longer every other weekends) that would probobly have the child seeing the non-custodial parent only monthly and then for longer periods during the school breaks.
You must not be in WA though, because CP is supposed to file a request with the court anytime they move the child out of the schoold district.
It also sounds like you are trying to work this out between yourselves and not go to court.
May want to try to line up some mediation before things get too heated and end up in court anyway.