As I remember... Amesz00 has fitted some aftermarket shoes to his truck that are supposed to have better breaking efficiency.
I have not seem any posts from him about this "mod", but I for one would be interested in knowing if using different shoes has made any difference.
Having said this, no matter what shoes you change to, the drums on these trucks are primarily designed to stop the truck when it is going forwards. so this change would likely make little difference in enhancing the braking capabilities when the truck is going backwards.
The only way I see to resolve that problem would be to convert to disks, but that is in no way a small change.