I just came back from a super hectic trip and I had a few instances where I just could not get/carry the food I needed. I never ate anything that wasn't OP but I did have to go without all of my veggies some days, here's some of the things that I ended up doing:
1) Carry bars. One day I had two, but that was after it was clear that I would have no opportunity to have anything else. I was fine with it.
2) I mastered the "art" of pouring the drink powder into a regular water bottle. It was not the easiest of things but it can be done, then you just shake it vigorously and it dissolves just the same as if you were using the shaker.
3) The night before I prepared 2 cups of spinach and even though I was not hungry at all, I ate it before I left home so that I ensured that at least I had 2 cups of veggies on busy days (I chose spinach because it boils down to nothing and so it didn't take long to eat and I didn't feel too full)
I think that the RTD is a great idea.
Good luck! You can do this!