I would add a bottle of both thin and medium CA for minor repairs and spares for every kind of fastener on the model, along with hand tools for every fastener on your models. I also keep a few small pieces of balsa on hand in case minor bracing comes loose. Your field kit should include a way to fix anything that would ground you for the day that you wouldn't mind fixing at the field. Cleaning supplies are also very handy to save your covering and keep fuel residue off of your interior. I used paper towels for a while, but then found that a microfiber rag for cars works much better and is washable. A little windshield washer fluid or denatured alcohol in a spray bottle will get the residue out of your seams.