do you have an enclosed area where you could lunge him before you go out a hack?
My point is hopefully that when you are lunging you are engaging his brain to go forward. Then when you go your hack his brain will still be thinking and going forward also when lunging you are on the ground and encouraging him forward by voice commands which again you could utilise when out and in a sticky situation when he's not listening to the leg. and again when lunging you are the one thats in control! instead of using a stick on the hind quarters or shoulder you could try the element of suprise with a schooling stick tickle down at the hock area (if you can reach) to again encourage the brain to move forward and away from the annoyance! You did say he was spooky so again an element of caution with that one! Or you could try rubbing or light tickly taps around his dock area to try make him go forward!
Most important thing is to keep calm and if you feel yourself getting frustrated take a minute before actually doing anything!

Good luck hun!