Some ways are definitely hard ways, but a lot of ways are viable.
In another thread, I just talked about this sort of issue. My favorite band of Battle Brothers thus far has been a group of two-handed weapon specialists where there are a few archers and a few shieldbearers, but the majority of the group wields two-handed weapons. They’re very effective at killing things, and they can wear some darned heavy armor, but they aren’t so hot when it comes to “not being made a pincushion.” Still, it’s very fun. I recommend trying it.
An all archer group would be really, really awkward to play, though I could see having mostly archers + some hybrid archer/melee combatants with Nimble and stacking Melee Defense. They could hold the line in emergencies.
I think Danubian has the right of it, though. You can run with an archer heavy group (even as many as 8, I think) so long as you have enough dedicated melee to support them as defenders. You need to carry a BUNCH of ammo, though.
One though I personally love doing in groups with several archers (say, 4-6) is killing goblins for their nets so my melee characters (with Quick Hands of course) can hurl nets onto approaching enemies, slowing them down and allowing the archers to brutally murder them. It’s funny watching bandits struggle to get out from those nets as arrows pelt them from your back line.
