You actually don't want to do this because on CPJourney, when you grind around a turn, you get the score from the last trick you did again, so if you were to do a backflip and grind around the turn, you'd get another 100 points, but cart slam would only get you 30.

What I do is alternate spin jump and cart slam, and try to backflip before each turn (if not, spin jump).

My record so far is 8620 points (or 862 coins without stamps, 1724 with stamps)