Help with bathing....

Try a shower chair and soap him gently as he sits in the tub, then wet the washcloth with warm water and wring out the water over him. He might come to regard this as soothing. They don’t like the shower noise. They don’t know that the wand won’t hurt them. Mom was afraid of her toothbrush.

Please discuss this with the doctor or Social Worker when you go to the VA. I hope they know that you are having problems with him.
They can approve aides as well that you will not have to pay for.
Sometimes it can take more than 1 visit to get someone into a shower or bath. Would you feel comfortable having someone you just met shower you?
And as mentioned showering can be frightening. The VA PT told me that the head and front torso area are "vulnerable" areas that a person will protect.
When I got my Husband into the shower I would start at his feet and work the way up the legs getting him wet. I would then hand him the shower wand so he could wet himself down at his pace. There were times I also put him in the shower backwards so that he was not facing the water but it would go onto his back. I would then use the shower wand and let the water flow over his shoulders.
I would often turn off the water so that the noise would be reduced as well.

A sponge bath with a good non rinse soap should also do a pretty good job.
Keeping his hair short makes "washing" his hair easier.

But if worst scenario if he is on any medication for anxiety medicating him prior to a shower is a good idea. It will keep you safer and it will keep him safer. Last thing you need is to be wrangling with a slippery person.

Something along the lines of when the A-Team medicated BA so he could fly on the plane?

For dementia, a spraying shower can be absolutely terrifying. A foot soak can feel like boiling water. My MIL responded well to the no-rinse shampoo cap as long as it was properly warmed. Hosing him down outside will cause a lot of yelling and thrashing and you could end up with APS at your door. Maybe trying some warmed baby wipes and only doing one arm or one leg or just the back or just the front in each session might work.