I've seen this done with Obito, when a cosplayer gets thrown into naruto and a second of that character, I like the idea. I also realized how much chaos it's going to cause the cosplayer, and the world. As example I guess with Rin, depending on the timeline, if Rin was already dead, kakashi is going to have a mentalbreak down. Also depending on the age of the character that is getting thrown in, like if Rin is alive, but your character is older then the og, but the hokage knows them... that be werid but eh.
I also like the idea of getting thrown into naruto, as any character, get people confused then meeting the actual character, and be called brother/sister and be introdusted as a twin lol.
I have the idea of giving the person thrown there the power to transform into any of there Oc's that they have, and the chakra nature/capacity/ signature would change too and can't be found out, or undone. Just an Idea.
If they're just thrown into the forest, at least give them an explanation and supplies, if not just give them money, and a simple note that says what they can do.
Oc can just be a random villager any were and sell stuff, and just have people or the village shinobi just see someone that is in the bingo book, but it isn't them.