Will this work in multiplayer with players that have different skins? Or will it make everyone have the same skin you select?

Sorry to late.

If all players installed my MOD, My MOD works on multiplayer game.
but this mean "Just no error".

This MOD only replace human image data.
In other words, on your screen, all player are seem same skin as yours. And also , on screen of your friends, You are seem same skin as your friend of, too.

(for addition ,if the skin has mask-image, they are each colored.)

Would this be changed in the future, so that way, in multiplayer, the mod would send what the host is using, over to the 2nd player, and same vice versa, so they were both different and not seeing the same character? Or is that outside the realm of possibility?
I think it is possible, but requires some more coding, seeing as players can have different colors, and they see them too

Thank your comments. and sorry to late my response.

I didn't think deeper for multiplayer.

Is "the mod would send what the host is using" means that host send his LOCAL-data?
if it is truth, host will update 2nd player's data. so, It is no good.
If it is not this mean, my MOD works. I think it.

I said that below:
Player 1(MOD replace image to "a")'s screen: PL1=>"a",PL2=>"a"
Player 2(MOD replace image to "b")'s screen: PL1=>"b",PL2=>"b"
That's all.
it's not (PL1=>"a",PL2="b") .