Just a thought, the bars in the tub may be too low for functionality. I have seen the bars suggested to be mounted at 36". But that is in a shower/tub situation I believe. I mounted mine at 24" above the floor for my tub only installation and it is a good height. I have another grab bar behind my tub for towel use and it is around 42" above the floor. My tub is 14" tall I think and 5' long.

I read somewhere to mount the centerline of the grab bar 24" back from the front of the tub.