You can get it done in two long days, with a decent sleep break in between. I've been driving trucks since '91 and haven't really felt the need to take pills. I did try one of those 5-hour energy drinks the other morning, at about 2 am, and I think the nasty taste kept me awake more than anything.
If you get sleepy, find a safe place to pull over, lay your head on your arm and take a 30 minute power nap. Long enough to rest but not really long enough for your body to shut down for the "night".
That works better than anything else for me.
Also, I download podcasts from here and a few other sites, including some aviation and bicycling stuff. It does a better job of keeping me alert and interested than music does. If you need to stop for a few minutes, by all means stop at a truck stop. Just make sure it ain't a dirty, seedy place, and stay on the car side (I'm assuming you aren't in a truck... if you are, you'd probably know where to go anyway). Find a decently lit place for your nap.