I bought my new to me 2007 Casita
from a couple in Georgia in 2018 and started a trip log (Excel) workbook to track usage and mileage. Along the way, I added sheets/tabs to build lists for items to take with me, a “pre-flight” checklist and mods/tweaks that I have done. As with any spreadsheet, columns and or sheets can be easily added for things like cost, gas usage, gas mileage, etc.
The spreadsheet is accessible on my (android) phone and on my PC. Naturally, I hesitate from updating it on the phone mostly because the combination of the size of the screen and the size of my fingers combine to make updating a horror story but I can view it there and, if needed, enter detailed updates on my PC.
I have posted a copy of my “spreadsheet” here
. Feel free to download/save a copy for your use.