V.B.
They make a booster called the "on the go" booster seat and I always keep one in the back of my car in case we go somewhere that doesn't have high chairs or to someone's house that doesn't have a kid. It folds up nice and small and, while it doesn't have a tray on it, you can pull it right up to the table. It only costs around $20 and Target carries them in the baby/kids section (you can look online at Target.com to see what I'm talking about...just search for booster). Hope this helps! Have a fun visit.