"Bathroom" access question

I'm a curvy woman with a stomach (American size 14-18) shopping for a warm full body suit (prefer long sleeves and legs) that allows for "bathroom" access - zipper that goes all the way to the back or possibly snaps? I would like to be able to pee and poo without stripping naked in the cold.

Help??

Edit: thank you for 'union suit" suggestion. I'm finding better options now. I didn't think to mention I have sensitive skin and need at least 60% cotton (90%+ would be ideal) not all or mostly polyester or other synthetics and no wool (I'm allergic).