Back in the days that I fished draw tournaments the back seater was always given the right to operate the trolling motor for half of the fishing day. I'm not sure why so many organizations got away from that. Hopefully you'll be able to take advantage of that chance.
Thinking of all the things I've learned here, I have to say that priority #1 has to be getting to the point where you can walk a limit of fish up to the scales. How you go about that is going to be the key. These are the things I would suggest doing.
Study, study, and then spend some more time studying! You need to learn the body of water you are fishing, what techniques tournament winners have been using there, and everything you can learn about being a backseater.
I've never fished this place, but i believe the Potomac River is what would be called a tidal waterway. This should mean that the prime times during the day will be during the changing of the tides when the river's current positions fish differently from times when the tide isn't running. You are going to want to find out what those times are for the day of the tournament.
I remember reading a few tournament reports in BASSMASTER about tournaments held on that water. If my memory hasn't completely failed, one of the most productive patterns dealt with fishing in, over, and along side some fairly large emergent weedbeds. I also recall reading somewhere about fishing old pilings and other rubble that provided current breaks or ambush points during those prime times. You are going to want to select lures that work both on top of those weeds like a frog, along with either jigs or a T-Rig with a pegged weight to get down through those weeds. I suppose you could take along the infamous senko, but weightless worms usually don't work very well when the guy on the trolling motor is zipping along at his own pace. I'd stick with something that gets down to the fish as quickly as possible!
You can also find a lot of good suggestions on how to make the most of being the backseater right here in these forum pages. Some are a little negative, but you will do best if you concentrate on those that show how to positively react to the challenges faced when you are in the back of the boat.
I think the most important thing you can do to insure getting those five fish in the boat is to remember that you have to take advantage of those prime times during the day. When the fish turn on, you want to be throwing you best baits at the best spots. Watch the angles your boater is giving you and work the lure that fits that situation.