You can bring sunscreen towelettes on the plane. I use Supergoop brand. They come in a big container size that has about 40 wipes in them, and a smaller container that has about 8 wipes. They are somewhat expensive (40 wipes for $13), but the sunscreen is very, very good. It doesn't sting your eyes, and it isn't greasy or heavy. For the first day of vacation, we use the wipes exclusively. Once we are settled at the hotel, I use bottled sunscreen on everybody before we head out, then use the wipes to take out with us to keep reapplying.
You can search for Supergoop on
Amazon to see a description. I can't post links yet as this is the first time I've ventured out of lurkdom here.
There are other brands, too. Hope this helps!