I found a paleo-friendly alternative to the American lunchbox staple that is the tuna salad sandwich: Tuna salad stuffed peppers! Having located a canned tuna that has only olive oil (no soybean or canola oil), I made a batch of tuna salad last week and stuffed it into the mini peppers that we had picked up at Sam's Club. The peppers worked very well as a tidy vehicle for transporting tasty tuna salad into one's mouth.
To make your own tuna salad, try making your own paleo mayonnaise - there's a nice tutorial over at The Clothes Make the Girl. Or, you could do the quick'n'dirty shortcut that I did last week - full fat sour cream (ingredient: cultured cream) mixed with a paleo-friendly salsa verde and some Bubbies relish (which has no sweeteners like sugar or corn syrups added) - all mixed with the tuna. Given the right occasion I would definitely serve these up as an appetizer!