Don't know how fancy you want to go, but here are a few ideas. Way back in the 70's before the adventure bike thing a friend of mine outfitted a Yamaha XT500 to ride the Alaska Pipeline (which was still under construction) to Prudhoe Bay. Having been cleaned out in a messy divorce he had to go pretty low rent. Here's how he got the job done
Scrap chrome moly tube from his stock car days for a frame and a couple of green 5 gallon plastic jerry cans made a set of tragkorbs. He cut the tops off and with a bit of trimming was able to put them over the body of the can. A nylon strap held the can in the frame and the top on the can. They were surprisingly waterproof, and lasted through 100,000 miles and every state but Hawaii, most of the Canadian provinces, and a trip to South America. Two metal milk crates were mounted side by side on a home brew luggage rack and along with other stuff carried additional gas in metal cans. The crash frame around the headlight had tie down points to carry his rolled up rain suit and other stuff. The bike was pretty ugly(he joked that he could park anywhere he wanted and leave the key in it), but in two years of non-stop travel it never let him down. Everything he needed to live for two years on the road fit on that bike.
Around 1979, at something like 105,000 miles, a Yamaha rep offered him any bike he wanted from their product line in exchange so they could strip his down and analyze the wear.