I've never understood why people think you need an enormous field box.

You don't. Put what you need for starting/tuning in your field box. Put all minor repair items (bolts, glue, tape, tools) in a second toolbox and leave it in your car/truck/van/trailer. Your cleaning and charging equipment can go in either box. A first aid kit also goes in the second box.

This way you won't hit yourself over the head when a shot of CA will get you flying again, but you don't have to lug all of your crap to the flight line.

Also, don't bring balsa to the field. If it needs balsa to be fixed, you need to do it in the shop, and throughly examine the entire structure for damage.