Since your hair is so light and you seem to want red, you could do a very light henna "gloss", which would add just a teeny bit of red to all the hair, and shine too. It doesn't change or lift the original color, just adds color, so you end up with multi-dimensional look. Henna glosses are done by adding a bit of dye-relased henna paste to conditioner, and applying like a deep treatment. For a light gloss, you could start with a very small a teaspoon of henna powder (dye released) to a cup of conditioner and leave on for 30 minutes. You can increase from there if you don't get enough color. The effects would be subtle, and it would be so much easier to do than trying to isolate tiny pieces to do lowlights. Extremely cheap too.

I can give more info on dye releasing if you're interested.