Have you tried doing it with a decal? I feel like that would be the quickest and most straight forward way to do it. You would probably get the best results with vertex painting the texture effect to the areas where you need it.
Thanks for the responses! I kept them as a light function (decals were a bit to tricky to size up) and found a better caustic texture to work with (helps to know the actual term.) With some tinkering I've gotten it looking a lot better. I'll post a new gif of it a bit later on this evening.