Too much "wiggle room"

Pinch is a fast worker.
This can make training really fun.
The reverse is also true.
We are taking a Beginning Utility Class and Pinch is loving every single second of his training. But in his enthusiasm and my greediness to do too much too fast, this class has exposed some training holes.
When I trained his signals, I had him stand on a small doggie cot so he would learn not to move forward. While he can work on the cot just great, turn the cot upside down or just put him on the ground and you have a dog that is all over the place.
Backchaining here we go again.
I have now made a small box that is perfectly Pinch-sized. He cannot stand and move his rear. I absolutely cannot move foward. He cannot inch up on the sit.
He's such a fast little guy and I need to get faster with my rewards and/or praise. Learning to mark the right behavior is every bit as important so he can learn what is right.
All releases are given moving backwards. Sometimes I place a treat behind him, and after he does his signals he can go back and get it. Other times I just throw a treat behind him to get. Sometimes he has to back into his signals. The message here: moving forward earns you NOTHING. Going back is goooooooooo-ooood. But I am, once again, only 3 feet away from him. But better to discover this now than have our Open title. It would be awful to have to delay a Utility debut because of a problem like this.
But we are having the time of our life. Went out this brisk morning to work signals and directed jumping and before I realized it 45 minutes had passed. It's great to have another dog like Shiloh where training is just so much fun you have to MAKE yourself stop!
So grateful for my little black flash!