Nice color combinations
Actually for me I wear trucker style caps, I have two and both of them are trucker caps (or the ones that have a mesh/net garment on the backside with a snap strap.) I love the trucker cap not only because i see it as vintage and good looking but also the mesh garment let more air into your hair in comparison to regular caps.
But anyway...I believe the style you're showing will better represent the Pistol Lake theme and style. And as @efriedman mentioned the strap back with leather would look good on them and complete the retro style. Also, the buckle you're showing (the full like-square shape one) is awesome especially if it has a vintage copper or distressed gold color, but maybe the belt buckle style @DanePetersen mentioned is more functional.
As for color combos:
- my favorite is white/very light grey front panel with black back and burgundy lid (the front peak part)
- A full Faded Navy one similar to the new Henley color from Pistol Lake. (It will look so good on a trucker style; to have the mesh color is the rest's)
- Heather grey with light-leather brown color lid.
- The military green one you're showing is amazing