I have seen similar showers at Home Depot...I guess whether it would work or not would depend on how & where you intend to install it. My first thought is the raduis of the ceilling/walls may not allow it to work. It may be too tall or need to be held out from the walls to fit...but I guess it depends on it you are trying to fit it in a corner or in the center portion of your trailer. Also, the walls of your trailer are tapered which would have to be taken into account - the fiberglass (acrylic?) panels that make up the walls of the shower are straight.
Or are you wanting to tuck just the pan in the rounded corner? That may work, but the raduis would have to be confirmed. I would also only consider an acrylic-type door, not glass. To much flexing in a vintage Airstream IMO.
Any additional info or pics you can share can help us understand what you are thinking...somes interesting and worth exploring ~