Having to keep up with receipts on a long overseas trip is a pain.
Yes it is. Fortunately, the rules have been relaxed to where you are just required to provide a few of the “heavy hitters”, lodging, airfare, rental car, shuttle, etc..
After my first AF TDY where I didn’t get fully reimbursed due to a missing receipt, I started taking a zip bag with me on all my trips. Every receipt went into that bag and I would sort them out when I got back.
I still do the same on company travel. I just never know when I’m going to get audited and this way, I can show the bean counters where just about every nickel went. I keep them for about 2 years and then shred them along with the expense reports.
Overkill, yeah, but I figured it was the best way.