EDIT: It seems that this has been patched now, so my method no longer works.
I've managed to create a park which just requires you to hold Y and takes a matter of minutes.
The park is called "Hold Y for 10m Points".
Just grind the corner rail right in front of you and continue holding . Your skater will get stuck but will continue to rack up points and "Kissed the Rails".
Just be careful when getting out of the grind!
If you haven't got them already, you'll also get "High as a Kite" and "Shoot and Score".