So sorry for your loss, as a father, I don't even want to think about losing my son. I was thinking about where I would place a memorial sticker on my YJ. On the new Rubicons, the front glass, behind the rear-view mirror, they put a sun shield in the shape of a classic CJ grill and lights. I think I'd have something like that made and place it there. That way, whenever you drive, you are always sharing the view with your Angel.
I work in marketing, here's an idea for that type of sticker.
So very sorry for your loss. God bless you and your family.