Need advice on traveling

La

I'm 12 weeks pregnant and have hypermesis gravidarum. I'm puking A LOT and get pretty sick. Well lately my puking spells have started to lighten up and we are about to make a 4hr car ride to visit family. I puked about 5 times this morning but I think it may be done ?? Anyways if I start puking 2-3hrs down the road what's the best way to contain it/prepare for it? I have bags but what do you do with the bags? Just go to gas stations and throw them out or???? Just what are some things you know to do.