Funny, I have exactly the same setup in the bathroom I just remodelled, and our second bath is also the same. 5' wide x 9' "deep", the tub is on the far end of the room and the toilet is on the drain/showerhead side of the tub.
The one thing that was really hard to find was a pivot door setup *for a tub*. They were all assuming a very small glass panel on either side of a 24" wide door that swings out. I found a couple places that could custom make larger panels on the sides, but then you're talking a lot of $$$.
I actually purchased a bypass set of doors from HD, Keystone by Maax. They arent the highest quality but for our secondary bath work just fine. They are as wide as the tub (5'). You say the current opening is 47" wide? Does the current bypass door setup go the width of the tub? I just installed the tracks on each end wall where the tub was, the door fits fine in that area. I know there is an acceptable range of widths the door can be used, I dont know what it is off hand. Wouldnt see why it wouldnt work for a 47" wide opening, but FWIW I have the door even where teh toilet juts out. Can still enter and exit the shower just fine