Welcome to Dementia Support Forum @L Ann.
I don't have any great advice, but this is a very friendly and supportive site and I'm sure others that have been in a similar situation will be along soon with their suggestions.
When my mum started displaying reckless behaviour was when I started to organise a move into care, but I'm not sure if that is something you are considering at the moment.
This behaviour sounds like something to discuss with his GP as soon as possible, but in the meantime could you put some of that sticky back plastic that looks like frosted glass onto the windows that you think he’s exposing himself from?