I have not done a 3 or 4 day credit card tour, my tours have been from a week to a couple months, with camping and cooking gear. But if I was going to do what you plan, I would probably bring:
- Two days of biking clothing, but probably 4 or 5 days worth of socks.
- Two tubes, I never only use one because sometimes the stem can separate from the rubber which can't be patched. But I have never carried three tubes. And tire levers. And patch kit. And one pump. I have only had one flat on a bike trip out of thousands of miles, that one flat was a stem that separated from the tube, but I still carry a second tube and patch kit just in case.
- I like a big complete multi-tool that has it all, plus a small tiny one to keep in a pocket. But, my big one is usually under the tent or some other hard to reach place, on a credit card trip I probably would just take the big one. Bring some disposable gloves too, if you have to fix a chain or repair a tire on a muddy route, you will be glad you had them. Next time you are at your dentist office, ask if you can have a few pairs of gloves before you leave. My big multi-tool has a chain tool. Each of my bikes has its own odd tool needs, I would carry whatever I might need too.
- A spare M5 bolt or two just in case you lose a bolt. I also carry a spare shoe cleat bolt. But so far my spare bolts have always gone on other people's bikes, I never needed to use one of my own bolts on one of my bikes on a tour yet.
- I store spare spokes on the bike and never think about them. In the seatpost, held in with a wine cork. The cork dried out and shrank, so I wrapped a little electrical tape around it to make it fit in the seatpost tighter. My multitool has the spoke wrench. Be advised that on tour most spokes that fail require cassette removal, for a 3 or 4 day trip I would probably not bring cassette tools and would instead just risk ruining a rim by riding on it too far with a broken spoke.
- Water, depends on temperature, hot weather I carry up to a gallon but cool weather much less. Extra water in the pannier is usually in a regular water bottle with tight fitting lid so it does not leak, not a bike water bottle. You can pour water into the bike bottles if needed later.
- Rain gear. This includes a rain cover for my helmet. If the motels you stay at provide plastic disposable shower caps, grab as many as you can for helmet rain covers. Some extra plastic bags like those used in the produce aisle can come in handy to put on saddle, etc.
- Cold weather gear, I use a down vest, a polartec vest, windbreaker, long finger gloves, Sometimes I shove a bit of plastic bag type plastic in the toe of my shoe to block the wind from going thru the shoe vents in colder weather.
- One day of street clothing, including sneakers or maybe sandals, but multiple days of socks and undies.
- Soap, shampoo, toothbrush, toothpaste, etc. Or if in motels, you can leave the soap at home.
- I carry a thermos for coffee that fits in a bike water bottle cage, but I suspect that 98 percent of other bikers don't do that.
- Generic place holder for communications and navigation stuff like phones, maps, GPS, compass, whatever you prefer and know how to use.
- Luggage (pannier, handlebar bag, seatbag, etc.) to put it all in.
- Lock.
- Minimal first aid gear, but it would include bandaids.
- Snacky stuff like granola bars, power bars, etc.
- Lights. Spare batteries for lights.
- Spare cash or plastic stashed somewhere in case you lose a wallet.
- Other riding stuff like helmet, sunglasses, clear or yellow glasses for night riding, etc.
- Touring, I use pedals that have one side for a cleated shoe, other side platform for normal shoes. If I get my cycle shoes soaked in the rain and it is dry the next day, I wear the regular shoes while the bike shoes dry out. I really hate wet feet.