Whenever I start my game, everything is fine, but if I fast travel, all the textures are messed up or missing, and things only return to normal after I turn off and on archive invalidation via NMM. I installed only one mod before the glitch, dragbody's Daryl Dixon follower. I moved the mod files into the wrong folder at first but deleted them, so unless one of the folders in the Fallout New Vegas folder is the same as one of the files in the Dixon mod, I don't know what's wrong. Can anyone help?
EDIT: I crash whenever I fast travel normally or use a mod to fast travel (e.g. mobile truck base), I only don't crash when I use the console to travel.

That used to happen to me when I had installed too many mods.

You're probably around 120 active .esp's, if your gun textures go missing mid-game and you're crashing on fast travel you've got the same symptoms as me. Deactivate all mods and only pick the best ones, start a new game if your old saves are messed up and can't be loaded anymore, which they probably can't, or have some sort of problems due to the amount of missing plugins.

First time it happened to me I just wiped everything clean and reinstalled the game, but that's probably overkill.

What he said, even though they say the limit is 138 plug ins, some people can go more or less depending on the mod combination, for me when I hover around 130 mods I'll end up with the same issue as you. You don't have to tabula rosa your game and wipe everything clean, just uninstall some mods and see if that it work, it works for me.