Overtraining is not just doing a lot of physical effort. As the term is normally used it refers to a chronic syndrome characterized by an inability to recover from a workout, even if you rest for what would normally be a sufficient amount of time. It is often accompanied by moodiness, inability to sleep, increased susceptibility to illness and injury, unexplained
weight loss and elevated resting pulse rate.
Your body can likely adapt to this work load without experiencing overtraining. If the job is relatively new, you could back off on your workouts (or at least not try to progress) until you get used to it. Leaving both days off as complete rest days should be plenty. While it's always important to remember that everybody is different, lots of people have physically stressful jobs and still benefit from working out.
For more on overtraining read these:
http://www.physsportsmed.com/issues/...603/hawley.htm
http://www.rice.edu/~jenky/sports/overtraining.html