Co angler can be very rewarding in the form of education...and very frustrating if you have a guy who doesn't care if you catch fish or not....simply put....bad boat positioning. You also have to deal with the fact that you are playing catch up all day if he is a fast fisher. I'd focus on having a good variety of spinner baits, crank baits, and top waters and limit my soft plastics to the necessities in order to save weight and room. Rods...shouldn't need more than 4 really. One spinner bait/topwater, one crank bait/topwater, one weightless soft plastic, and one jig/worm rod. That should cover most of the bases.
I don't know what sort of tackle boxes you're using, but I use the soft sided bags that carry the clear boxes. If you are running that kind of set up with your normal stuff, you might be able to save some $$$ by just buying the bag and transferring the clear boxes that you need. I keep mine organized by color types rather than by lure type like most people. That way if I am facing clear water, I reach in and grab my clear water boxes which contain all the lures I need for clear water. Same goes for stained, muddy, etc. Just one way to look at it.
Granted, take my advice with a grain or two of salt. I've only been co-angler a couple of times before I got out of tournament fishing altogether...so I'm no expert.