Hi, sorry you are having this trouble - it was really wearing for me when my husband went through it.

What worked in our case may or may not help your husband - but I have seen the remedy suggested somewhere in my extensive reading about Lewy Body difficulties.

Before he began 'sundowning' it was normal for him to visit the toilet 1 or more times at night, he would then nearly always return to bed.
When he could no longer find the light switches I installed night lights since he might void himself in the floor if he couldn't find the bathroom.

I didn't realize for a long while that the incidence of his sundowning skyrocketed following the adoption of nite-lites and found the (possible) connection by accident.

One night I was worn to a frazzle by his late night activities and decided to turn the nite-lites off in the hope that if he couldn't see to go then he might stay put.
His restless tossing and turning which preceded his jaunts at least helped me know where he was without having to get up. I'd just clean up the mess if one occurred.

Imagine my shock and joy when he slept like a baby nearly all night the moment the nite-lites were removed. He didn't wake up at all until he actually needed the toilet.
The old 'can't find the bathroom' trouble recurred, I addressed it by obtaining lots of cheap battery operated stick-on motion sensor nite-lites and placed them where they would only trigger if his feet hit the floor. Others would light the way to the bathroom as he progressed, they had auto shut-off after 15 seconds.
Now he could return to bed with little or no encouragement but if he became argumentative about it usually getting out of his sight would help.

I shared this possible solution with someone on another forum and she poo-poo'd the notion on the grounds that her night light was only a small one - and thus could not be a problem.
In my experience the room needed to be perfectly dark.

That's my lick-hope it helps, if not hope you hit on something that does help.