I am in same situation...
My DH works on building sites, but, 99% of them are powered, so, he takes a breville maker with him, and a couple of ham and cheese sandwichs. I butter the outside of them, so they dont stick, and wrap them in greaseproof paper.
My DH has a sweet tooth so, his lunch box is generally:
2 ham & cheese sandwichs
3 museli bars
1 50-60gm (normal size) choc bar, OR 2 10-15gm (treat size) choc bars
2 cans coke
1 600ml mocha
1 container of some form of cake or slice that i make

& a bottle of water.

occassionaly, as an extra treat, small packet of biscuits, or some saos with vegemite.