I have used the backerboard in mobile and fixed applications with great results.
As stated previously, the subsurface is just as important. Tile cracks from movement of the subsurface it is attached too. Get that right and your halfway there.
In the coach I only attach the tile with the mastic adhesive, It is much more forgiving than thinset to vibration. (my experience)
Like Coachconverter, I tend to overkill a little, but, have you ever tried to add backerboard once the tile is down?
Once and done!
Best of luck on your install,Cliff