This is a sensory issue most of the time and it is hard to get around. My daughter has a similar problem where she will not wear layers. This is a big problem in the winter because she does not like to wear a jacket or sweatshirt over her shirt. We sometimes just put the sweatshirt on by itself.

When we travel in the car as soon as she gets unit the jacket comes off. She does not like a hat and gloves either. We use a reward system to get her to wear things but it takes a long time for this to work and we have to start all over again every winter.

I really would let him wear what he wants. My son had to wear a light jacket, even in the summer, but it made him feel comfortable. He might not like the feel of the lotion and for the bath I to would get him toys to play and make it a night play time for him.

I was having the same shower issue with my 3 yo son. I bought him some new bath toys and threw in getting a sticker after shower time.