Never seen it spelt like that before, have seen - Paighton
Middle names are tough for that one!! Although if you have a first name finding a second name to fit should be relatively easy - just trawl through the book. I tend to go for something more traditional for the middle. Payton Jane, Payton Marie.
Ila is from the word Island, probably french in origin. Isla is another, more popular spelling, pronounced the same though.