The biggest, most monstrous dildo you can find.
He never uses it. Just befriends it and talks to it like in the original. Just leave the possibility hanging there.
For the entire duration, he can’t work out what it actually is because it’s such a weird shape and so ridiculously huge that it being a dildo never even crosses his mind
And instead of Wilson, it can be called Doc, or Dr Johnson. (Having a name like bad dragon seems a stretch, maybe baddra?)
Latex fist.
A tennis ball.
Magic 8-Ball
This time Wilson can kinda sorta actually talk back.
An MRE. When supplies dwindle, our protagonist is faced with a tragic choice.
couch cushion
This is inexplicably the best answer yet. Everyone else is working so hard to think outside the box that the box is inside-out.
Plus, now you can include a love scene.
I have absolutely zero interest in making this movie political.
Then I’d go with airplane seat cushion instead.
The couch cushion works fine. Couch cushions appear in real-life situations all the time and simply having one in the movie cannot be construed as making a statement on the kind of conduct that we as a nation are willing to accept from our vice-presidential candidates.
A coconut. Those who know, will know. Those who don’t, may their innocence last forever.
A fleshlight.
A bowling ball. Can change some of the script so he catches it before it rolls off the raft but he falls in the water with it. He’s too heavy and weak to make it back to the raft so he has to let go and watch it immediately sink or he’s taken under too (also a good reference how it’s hard to save someone from drowning when you’re near drowning yourself). Definitely thought of a dildo first till I saw everyone else put it up though.
Some bowling balls float.
Oh wow look at what the tides have swept ashore. A Pringles can, some rubber gloves and a few sponges.
deleted by creator
The severed head of a man named Wilson.
Oooh, the dead body of Owen Wilson.
Or the frustratingly unkillable body of Wade Wilson (Deadpool)
HEADPOOL!
A dakimakura, AKA a body pillow. Needs an anime character on it, obviously.
Of coure the large breasted, scarcely dressed waifu of questionable age shall still be referred to as “Wilson”
a super valuable in-the-original packaging giant boba fett action figure, he’s tormented by keeping it mint in case he ever gets back, somehow the rocket launcher ends up saving his life.
A pot plant which he might try take care of for a while before realising it’s plastic, but has already grown attached to it.
Me. I’ll play Wilson. Listen idk what the fuck that last guy was doing but my take on this character is gonna be a hit, you’ll see
Coconut would be believably available on the island, and you could have a whole arc when he runs out of water and fights over killing his friend to drink the juice, like a schizophrenic episode
Plus the sexual tension.
Step-coconut what are you doing?