It's really very simple. I input each flight into my phone (Google sheet) after the shutdown check is complete as I wait for pax to leave. Copy/paste it into Excel when I get home from a trip. Takes hardly any time at all. My Excel has every bit of info I can think of for an airline app, plus calculates annual per diem deduction for me using both base rate and location rates (to see which is more advantageous tax-wise).