Some players don’t want a career; they want a sandbox. A max level mod turns CS3 into a destruction-derby-slash-construction-park where you can spawn a $2M road paver just to see how it drives.
If you are determined to experience the game at its peak without waiting six months, here is the safest pathway. Note: Modding violates the terms of service of most app stores. Proceed with caution.
You can hire the maximum number of AI drivers (usually 5-7), allowing you to run multiple passive income streams while you personally operate the "top" machinery.
Use this only if you have a second device or don't care about your original save.