It might be easier to send youself spinning by just launching off the ramp at the atart and skipping the drive-sideways part altogether
thw problem is that there isn't enough downforce to arc over to the checkpoint area after the tunnel and upside down path
yeh; looping around like you did beforehand builds up enough speed, but that takes up time... Hug-0 had a neat shortcut to solve that -- might want to check it out, although I'm not sure how easy it is
I think the ultimate combo would be my first big skip on the first loop
The second time through you run it like normal
And the last time you do Hug-0's skip
I think that'd be fastest