I've done this in the Toybox ...
You first need a car (Cars Pack or Incredibles for example) and the fan (I unlocked it in the Disney Infinity Vault).
Go into the Toybox and placed the fan (several are better).
Now you have to jump the car to the fans that the car floats in the air. Now you can perform many tricks (with the right stick).
It is important that you remain in the air for as long as possible, make a lot of tricks, and then you land the trick clean (otherwise it does not count).
It may can be that you have to do after landing still a little trick on the floor that you see the experience.
With this method I have used approx one hours per character to level 15th.
Another tip: do this in a complett empty Toybox. Then there are no opponents.
I hope i could help.
PS: Sorry for my horrible english
Thanks to vSully for making this Video: