While this article is to help you create your own overlanding checklist, not to provide you one.
Although 75% of most overlanding kit is roughly the same across many adventures, the nuances and particulars of that 75% can vary wildly across price, need, redundancy, preference, and even simple availability.
The remaining 25% of your gear is specific to you, your overlanding rig, your location, and even local laws. To begin, gather up basic checklists for camping, cross-country driving, off-roading, and even international travel. Use the contents of those lists to create a general overlanding checklist based on your intentions, vehicle, and participants.
Often overlanding checklists are broken down into categories, and those further subdivided into individual items. It is good to begin with general categories so you can see where overlap will occur. Otherwise you will be driving a too-heavy vehicle filled with way more than you need. So much so that it may even ruin your trip.
An overlanding checklist should also be both digital like a note on your phone, as well as printed out. The reason for the digital copy is to always have it with you, and can easily be edited and shared. The paper copy is for when you need to work with a hardcopy because the electronic one is unavailable or not as flexible for your planning.
Overlanding Spreadsheet Checklist
Spreadsheets are great tools for building your list. But avoid using too many of the digital-only features since you will need to print it out as well. Something you can add to your checklist is also items you would like to have someday. When overlanding, you may encounter opportunities to acquire or upgrade vehicle parts and gear, and having those on the list as well can make the decision easier. I remember while in Moab encountering an overlander from California who had the factory rear bumper of his Toyota FJ on his roof rack. His FJ was now sporting a steel bumper with swing-out storage. He told me he found it on Craigslist while in Orey, Colorado. It was just an internet search on a whim while in a coffee shop because the overlanding rich area of Orey was a good place to find gear.