When you preload, try to push your body towards and past your stem, this is only achievable when you're at an angle though. Should really help you.
And don't forget about the landing. It's just as important as the take off. Kick the back wheel out so it lands before the rest of your body weight, then move your body forward to keep you from going over the back.
I know you're not really into TGS but watch Damon or Neil gapping. Their styles are perfect!