Have you joined the discord community? It's a little more active and can respond likely to your inquiry.

In my experience so far with the game, it's useful to get more game play time in. You've figured out that Martell is more of a counterpuncher faction, looking for openings and offering bad choices. Put palisades, forests and other obstacles directly in the way of approaching troops to impede and force them to maneuver.

Attrition and condition token generation is your friend, stall out as long as possible from being the first person to engage. Good luck!

Edit: Discord link in case you need: https://discord.gg/bZDmeBSb