... and you can do anything you want.
A few considerations.
> It seems unlikely that a contractor, no matter how experienced, will know anything about remodeling an Airstream.
> If you decide to sell, it will be worth less to some if there is no shower.
> If you do remove the shower. I suggest you integrate the space into a large, bathroom dressing area. Potential buyers may love the feel of an expanded bathroom/dressing room.
> Yes, by all means save and protect the uncracked shower stall. It may be the only one in existence.