We have a shower over the bath but pre-dementia, my wife always preferred a bath. As her dementia progressed, it became more and more difficult to get her to sit down in the water. She would get in then it was almost a wrestling match to get her seated. I even purchased a lovely PVC "bench" you could place in the bath, which worked for a few times but then we were back to square 1.
Like your husband (and many with dementia), my wife hated getting water on her hair/face, so Friday " bath time", became a dreaded battle of wills, resulting in several near misses (soapy baths can be treacherous places) and a strain on my poor back!
So in desperation one week, I simply climbed in the bath with her. At first it was a bit of a struggle, as she would tend to try and grab hold of the shower curtain. It helped that our shower is not the fixed head type so I could start off with the hose/shower head down low, washing her hands and getting her used to the water. This enabled me to work my way around and wash the rest, finally finishing with washing her hair. She seems to have got used to this routine now and for the moment at least, Fridays are less traumatic (if a little time consuming).
The rest of the week we make do with soap, flannel and wet-wipes.