Rally course ideas, suggestions?

[PWalk]

Hey everybody,

I am currently working on building a true rally course for the Bit's.

Currently carving it out a 4" thick piece of packing styrofoam that measures appro. 2' by 4'.

There will be dips and valleys all leading to an uphill section at a grade to where the bits will be able to climb it.(i.e. only about 10-15 degrees)

I'm using different grades of sandpaper epoxied down to the styrofoam for the roadway to simulate different textures in the road.
If anyone has any ideas, comments or suggestions I'd appreciate hearing them.
Thanks in advance.

p.s. this will be a course designed for torque and driving skill, not speed.