Are there any good products that are substitutes for vegetables?!
There is a low sodium V-8 juice. Even convenience stores and fast food restaurants have veggies and dip now.
For road trips of short duration, pack a small insulated bag with healthy snacks and a blue ice like you would use in a lunchbox.
You can also drink V-8 Splash or other fruit/vegetable mix juices. Several companies make them.
For times when you absolutely cannot get to vegetables, grab fruit. Whole pieces of fruit like apples, oranges, bananas, grapefruit, peaches and plums can withstand lack of refridgeration for several days.
Well if you wanted to you could dehydrate vegetables and bring them with you, but I don't know how good that would taste. If it's a road trip you can easily store raw veggies in a cooler, though, so that's the best idea. (They will keep in a room temperature car for a couple of days probably, but they'll taste better in a cooler.) You can also use just-add-boiling-water meals (like dehydrated veggies and pasta) because most rest stops have boiling water for coffee.