How do you use the bathroom when you are with your dog?

I’d like to do more solo day trips with my dog but running into the issue of using the bathroom. Yesterday I ended up stopping at a gas station that had a fully covered filling area and opened all the windows before quickly going to the bathroom. I was gone less than 5 mins.

How do the rest of you handle this? Any suggestions?

Edit: I should include my main issue is the heat. It’s 80-90 degrees and sunny year round here. She’s not reactive and has no issue being in the car by herself.