hi thorpelyon
sorry in advance for my cluelessness !
if it is a modern camera ( fuji or mamiya ) and you crank the winder
i don't think there is a way to modify the advance mechanism to take 220, unless
it is an option for that particular camera ( maybe the internet has a hack to add the extra frames? ) .
there are other cameras ( including tlr's like the yashicas ) that had a way to shift the pressure plate in the back to allow for 220 .
if it is an actual old ( like " vintage vest / strut camera" ) folder ( if you like the meniscus look maybe think of something along the lines of a 1920s box
or a hawkeye or panoramic, try an autographic 122 ) i'd burn a roll of film and see how many winds it takes to go from one frame to the next.
put gaffer tape ( or other light proof ) over the ruby window and tape your map on the back of the camera and have fun. just make sure your tape is really light proof. i did this
with an old roll-back and the tape wasn't as light proof as i had hoped and i got a light streak across the whole roll ...
ez to fix "these days" with modern tech, but a PITA 25-30 years ago ...
have fun on your trip !
john
ps. don't worry about all the " just get some 120 film " people, they sometimes don't get it