Little known fact about the game- although special boards (like the rocket) can't save times in time trials, they can get coins.

Here is the new route. It gets the rocket much earlier.

Get two time trial coins to unlock Level 2 Boards

Beat all Slaloms and use Slalom boards in Match Races afterwards

After you unlock the Rocket, use it to collect the remaining 16 coins. This will save minutes. And you won't lose anything from doing Slaloms with the Level 2 Board since you need to do lots of turning anyway. In fact, during playtesting a new 100% route, I wasn't just getting trophies with the Level 2, I was getting them faster. They are also faster than Level 1 Boards.

Everything else is as usual- just do time trials later and with the rocket board.