My friend and I did some preliminary testing on this game awhile back ago... The main difficulty in planning a route is the large number of goals you have to complete inside each level. For example, in level 1, some of the more complex goals are to:
-Get the slam move (to break open trash cans for tokens), requires 80 tokens to learn
-Find the 4 screws and take them to the roller coaster
-Get the Dune Dog car for faster movement and a few tickets (requires 50 tokens to use)
This is a preliminary testrun up to getting 80 tokens (at that point it's best to save and quit so that we can get the slam move):
http://dehacked.2y.net/microstorage.php/info/5779/RoutePlanning.m64
Here is a mostly optimized version of the first few parts:
http://dehacked.2y.net/microstorage.php/info/5780/Rocket%20Testrun.m64
And, on a side note, I discovered that the race with the corn car can be done without the dune dog by riding the corn car (it's very difficult, though). I have a movie, but I can't host it at microstorage because it starts on a savestate.
Edit: A few other notes about optimization:
-In the first level, there are a number of extra texts. Most of these take a long time to move through, so we tried to plan out where we could cancel out the texts. The "first ticket" text at the very start is skipped by landing on the ticket switch, the "first token" text is skipped by entering the midway, and Tinker's "sensor array is cut" speech (activated by getting a ticket in the first level) is canceled by landing in the exit of the midway.
-We discovered that the ticket sitting on the platforms in the water can be collected by driving the dune dog towards it, hopping off the edge of the water, and jumping out of the car onto the platform.
-There is another break later on, in level 2 (paint misbehaving): we found that after activating ticket D (where you paint the giant objects; collecting it activates an event where a building emerges from the ground), you can drive the paint car from the slope above, into the ticket, and far enough forward that the rising building will carry you upwards, starting you on the roof. This allows you to grab the ticket on the roof, enter the building from above, and complete the whole room backwards!
By the way, I can't promise any progress on this (it was just a side idea for my friend and I), but I just wanted to share this information.