It'll be interesting to see how long they last doing it that way.
We've been feeding a lot of hay at night when it's cold... I might consider reversing when you give them access to the round bale. Let them nibble all night, since your riding time will cut into the day anyhow, and he may not have a full stomach yet in the morning. It might work out that if they've been eating all night and you pen them in and feed breakfast a few hours before you ride he'll be just about the right amount of fueled up and digested then. I dunno, just food for thought.
You know, that's a very good idea.
Becky