All you have to do is go down the hill like you normally would and then after the truck crashes use the Super Bounce [In case you don't know how to do it start spinning and then spin into a wall and just before you hit the wall and and use the bounce attack like i said last time this is a rather hard teckneak to master] and after you bounce all the way up past the Gun truck and the invisable wall and know look
like you are standing on nothing jump down and the truck is crashed and you are on the wrong side do the same thing to get back when you are done.