We bought just the basic (read: cheap) Fisher Price portable booster. I looked at Babies R Us and just picked it out. It's fabulous! We've had it for both my kids and it works really well. My son is 21 months and is off the charts for height and weight and he can still use it. It straps onto a regular chair and is easy to clean, use and carry. It comes with a tray that you can use or not use. You may just push your child up to the table and he can eat from the table, it does have a seat belt so you needn't worry that he can climb out.
I would recommend that he eat in the stroller while you're just out and about, but I totally understand the need for a high chair! We usually just carry on this booster when we travel by air, but I have shoved it in my giant suitcase before when flying by myself with the kids. Have FUN!!