Since the bathroom door swings in, why not have the inner door removed and install a door on the outside of the door jam that swings out? Just make sure you choose a left or right hinge door depending on the outside walls. Don't forget to see if a floor molding door stop can be installed to protect the outer wall or door surfaces.
Me, I've always wanted bed room and bath room doors to open out instead of in as it makes the smaller rooms seem bigger - if there is enough room for the door to swing out without interfering with traffic flow. My master bedroom bathroom door swings out and that's how I prefer it. Of my three bedroom only 1 "needs" to have the door changed so that it swings out instead of in, the one at the end of the hall. I suspect that since yours is at the end of a hall that you can get away with converting it to a door that swings out. Just make sure that you turn the latch tube assembly around so that it locks correctly.
