You make some very good points and I like the period piece elements myself, which is why I am playing a nationalist German.
Which is why I think have one or two characters from a slightly more modern or at least culturally advanced society, who would appeal to such men from the 1920s, pointing out that they're being racist dicks, would make for some interesting inter-character drama or maybe even conflict. However, one has to be careful with accepting such characters or the story, as you pointed out, may become unbalanced.
Now, as to goals, conflicts, heroes and villains, well there are several different possibilities.
First and foremost, survive to see another day.
1. Return home, this would mean keeping the Errant is good enough repair and supplied with some sort of fuel, to make the attempt to sail into storms, in the hope that doing so might return them to the world they came from.
2. Build and maintain a settlement, in which to live for the rest of their lives. Maybe the most mundane option but in a world of monsters, raiders, warlords, subhumans and non-humans, there will be plenty of excitement.
3. Build a nation state. Ally with or subjugate natives to create an army, while using knowledge of 'modern' weapons and tactics to conquer those that oppose them. This would also entail keeping the Errant repaired and fueled and refitted with weapons of some sort.
As for pro-/antagonists, well thats going to be fluid.
One last thing, your avatar is highly amusing.