I think for a trip like that, I’d just take a pair of underwear for each day of the trip there and do laundry the first night at your dad’s place for clean underwear the next day. Laundry again the night before leaving so you have a full set of clean undies to get home again. I’d bring 3 shirts and plan on doing sink laundry the third night. Then just re-wear my shorts or sink wash depending in how dirty/gross they get. Underwear don’t take up much space, so to me it would be worth it to bring and have a clean, dry pair every day on a shorter trip like that, where you’re saving space not having camping gear anyway.