Just wondering how to get around this happening again basically! Last week, I was travelling home from a camping trip - just me and my 2yo dog. It was a blisteringly hot day, dog was in his crate and the air con was on. However, a 1.5 hour journey on the motorway turned into a 3.5 hour one due to traffic. I was absolutely dying for a wee but couldn't work out a way to stop at the services and go without leaving him in the car, which I obviously couldn't do. Annoyingly, I had a portaloo in the back of the car, but way too much other stuff in there to be able to access it without unpacking the whole car. Anyway, I didn't stop and wet myself about 5 minutes from my house 
Don't want to be in that situation ever again, obviously! But I often travel alone with the dog and I can't work out what to do. If I were in a town or village, I would look for a public loo, but I was on the M42 and options were limited by the time the traffic started moving.
What do other line traveller dog owners do? Thanks in advance :)