Since I often have to turn in the actual receipts, and (like your upcoming schedule) often have several back-to-back trips that have to be documented separately, I keep a series of envelopes available.
In the old-day, I hole-punched them and put them in my Franklin. Now, the envelope for the current trip is in a special, easily-accessible slot in my breifcase or backpack, and the other envelopes tucked away. Then, when I work on my expense claims, I pull out each envelope in chrono-order and it is easy to finalize.