The EASIEST way to do this is to enter an online
Tricks Battle game from the
Rider's Ridge area.
In this mode, your team can capture trick features by land a trick on them. If an entire section of the map is under control of your team at the same time, it will be captured and generate 5x the points for a certain amount of time.
Once captured, you should be able to easily grab a 75,000 point trick by grinding a longer rail, or hitting a double Misty/Rodeo flip with grab move.
You can also grab this in career mode during an event where you can combo many rails together, but this is not as easy.
You can also use the One-Foot board while you do this mode for another achievement: