I have the same problem with our son. I've started whipping up drinkable yogurts, using plain/vanilla yogurt and 100% juice to thin it out. I also send veggies with homemade hummus, crackers and cheese, and salsa and chips (we brown ground turkey and add it to our homemade salsa). Hopefully some of these appeals to him.
Also, you said he doesn't like spiced chicken but plain is too bland. Is it too bland to him? or you? You could send some sort of sauce for dipping, like BBQ or something you find that he likes...just a suggestion.