My wife and I camp-toured on our tandem. The total weight we added to the bike was 44 lbs. without food or water. That's everything for the two of us, starting with a naked bike with bottle cages weighing 36 lbs. Of course a couple can travel much lighter than the total for two separate individuals. We mostly camped, buying food as we went, and stayed at indoor lodging usually every 3rd or 4th day, where we showered and laundered. We had gear for summer rain and going out on the town in civvies.
Most of our gear was the same stuff we take on our 10 day backpacks in the mountains, minus the packs and heavy rain gear, and plus the civvies and bike rain gear. We went to REI and Feathered Friends many years ago and spent a whole bunch of money on light sleeping and tenting. We use a 3-person double wall tent so we can bring everything except the bike into the tent when it rains. If you want to drop weight, try looking at Big Agnes and their bikepacking tents and down bags with built in pocket for an ultralight Thermarest. If you're a couple, see Feathered Friends and get a double down bag zipped to a Toucan. We have a Seedhouse SL3, ordinary backpacking tent. Yeah, so basically to go lighter, you spend money, but only the once. This stuff lasts almost forever.
We don't carry a lot of tools, just what's necessary for normal bike tune-up and light repairs. Spares are mostly what we take on every bike ride: spare cables, brake shoes, chain oil, spare tire, spare tubes, patch and boot kits. We only toured in the usual fairly civilized settings in the US and Europe.
We put everything made of fabric into waterproof compression sacks. The tent (could be wet) went into a plastic bag which went into a compression sack followed by our sleeping bag. We each had a compression sack for clothes and one for both of our dirty clothes. The problem isn't just weight, it's volume. More volume = more weight to hold it all.
Besides keeping the weight down, we paid some attention to aero, since that's a tandem's strong point. I'm not a particularly strong rider and my wife puts out about 1/2 my watts so we didn't have a lot of power. We could cruise all day on the flat at 18mph because it's a tandem, though our low climbing gear had to be a 26 X 34. We tried to tour only on asphalt, though in Europe we did some brick and dirt following bike routes. We had fairly fast tires, 28mm @ 115 lbs. We never had a flat, just a lot of fun.
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