I suggest looking into the miniature carrots.  They would be bite-size.  Check to see if your grocery store carries them. 

I also suggest celery sticks.  The grocery store I shop at carries these celery sticks in addition to the celery bunches.  I find the celery helps add fiber to the diet, and that helps you "feel fuller".

I would also buy a head of cauliflower.  Cut it up into bite-size pieces, put them in a container, and you can take them to your shop fridge as well.

Get yourself a small microwave for your shop (if you don't have one already).  You could take a potato, pierce it with a fork, put it in a microwave safe container, and microwave it. This would be healthier than the chips.

Get yourself a small slow cooker.  Get yourself some meat - chicken thighs, chicken breasts, pork chops, beef, any of them.  Put them in a slow cooker in the evening, also with some salsa product - homemade or store-bought.  In the morning, put your meat and salsa in a container and take it to the shop with you.  If you have your microwave in the shop, you could heat it back up when you are ready to eat it.  Maybe you don't want to do this every day, but it could kept in your menu rotation.