Bring a microfiber cloth (like the ones for cleaning glasses) and a spray bottle with an acceptable solvent wherever you go. It doesn't take that much time or effort to clean every few days.
Using a solvent is actually a very unwise mistake. No solvent is required and you're just eating away the coating. You don't need any solvent at all. Just a cloth and very occasionally, a couple drops of water. That's it. If you are cleaning your screen every few days, you're doing it wrong. Stop touching your screen and dabbing it with slices of pizza or whatever the fuck you're doing to get it dirty "every few days".
I agree that solvent is unwise. My original (GP) question was about keyboard covers, which often end up touching the screen (when the lid is closed) and transfer finger oil onto the screen.
