One of our senior teachers likes to say, "You don't need to hold his wrist. A finger is enough." Uke tends to find this disturbing, though!
For myself, I find that when I am failing to keep hold of the big-handed guys, it's often because I am forcing the technique in the first place. On the rare occasions when I manage to lead lightly and smoothly, I don't lose hold. Of course, this is easier to know than it is to fix....