I’m in the process of doing one now . Tore out the garden tub . Built a kneewall , used the Kerdi system including the pre sloped 48”x 72” pan . Had to extend it with dry pack but not bad at all . I had hardi backer on the walls and it was drying my thinset out real quick while trying to put the membrane on the walls . Ended up using a pump srayer to wet the walls and then the thinset was good and wet for awhile . Just make sure all is plumb and level and take your time with it . It is a very good system when done right . Utube has some good tutorials . I wanted to hire it out but its hard to find good help in Barbour cnty so i tackled it myself .
Good luck with the project
If you were closer i have some materials left over i’d donate to the cause