I didn't work 40 hrs, but I did work 20-30. Its difficult, but looks like you are doing well with GPA, this time management will help for the MCAT, Med School, and beyond. However, When you take the MCAT, you better know yourself well. There are people every year that work 40 hrs, and get a 40 on the MCAT, but those are few and far in between, so see if you are one of those. If not, save up money to cover that semester so you can work less. Better yet, even take the semester off if you can make up the classes and still graduate on time. This will free you up more for MCAT. Its doable, but guage yourself to see if you can do it.
Also, if you are working that much, you probably don't have time to do research or get clinical experience. With only 20-30 hrs of work, I did have time for volunteering. From what people tell me, med schools, at least mine, will look past that if you have a strong history of working, especially if its in the medical field. However, do try to volunteer when you can (if your job isn't related at all to medicine). It will not only show med schools that you have some experience and are genuinely interested, it will solidify your own interest in medicine. Good luck.
sscooterguy