I think if you have the facility to take two carriers without too much trouble, you should, just to see what trouble Lucas is going to be. Then, when he has to go, you'll know what preparations you need to make. If he makes too much fuss this time, you can change your mind even at the last minute, and leave him behind, but whatever you decide, you'll know you've done it for the right reason, for the cats' convenience rather than yours.