I keep mine on with a xxl bra just cut a small hole for the tubes.I'm jealous you can pump while driving. I always wanted to do that but can't think of how I would conceal them and not have them come off. I get enough honks from truck drivers on the road Noogling could end up being really dangerous for me.
I have seen some cups that have the tube's that 90° down. Can't remember where I saw them. They would be great for pumping with a top onI keep mine on with a xxl bra just cut a small hole for the tubes.