Driven by some frustration about the inability to change my character's name, I went looking for some information on how to do so and stumbled on how to do so precisely. I'll list the steps below for anyone who might also want to change their character's name. Perhaps it'll be easier in the future with the use of a save editor, but for now this is the method that I know of and that works.

Fair warning though, it will most likely break your in-game photography album pictures, so if those are important to you, you might want to try to export them in some way.

• Step 1: Navigate to the game's save data, which you can find an example link for below of where it was located for me, with my ID scrubbed of course, but unless you're sharing the computer with multiple other steam users, there should only be one there. The string of numbers after the steam user ID is the ID for the game itself, which is a static constant across all users.
  
  "C:\Program Files (x86)\Steam\userdata\[user ID here, it's unique for every Steam-user]\1446780\remote\win64_save"
  
  
  
• Step 2: Create a backup of this folder, the easiest method of it is to simply copy the entire "Win64_save" folder onto your desktop, or moving it there outright, as this could make the next step slightly easier or let you skip it outright.
  
  
  
• Step 3:Delete or remove the "win64_save" folder. Make sure you have a backup as, if you delete the thing and emptied the trash can without a backup, your progress is now gone basically forever, unless steam's save backups are enabled and... honestly I'm not sure how to make them install the saves again, maybe validate the files? Either way, don't take any chances.
  
  
  
• Step 4: Create a new save and character. Yup, this is exactly what it sounds like. Customise the character to your heart's content, including giving it the desired name, the cat and dog doesn't matter as those will be overwritten by the last steps of the game.
  
  
  
• Step 5: Save and exit the game as soon as possible, then COPY the "data001Slot.bin" file from your backup into the game's save-files on Steam and reboot the game. Don't worry about the various files with SS1 as part of the file name, those are the album photos.
  To explain step 5 succinctly, "data00-1.bin" seems to store the hunter's customisation options, including name, while "data001Slot.bin" stores everything your hunter has done and owns, including gear, items, item chest contents, weapons, palamutes and palicos.

Enjoy, and for those who might be curious about where I found this and how it was originally written, I will copy-paste it below.

"1 Backup your save
2 Delete save in system
3 Start a new game,name your character and make a new face.Cat and Dog doesn't matter,they will be covered
4 Backup your new save
5 Put data001Slot.bin from your first save into second one,this is your character's game data including every thing without your hunter information
6 Restore your second save and enjoy
Might be a little confusing cause i am not a English user but you got this."