If it turns out Space Haven doesn't have a peaceful option (I believe they don't really support mods either), check out Stardeus.

You can definitely get Stardeus to be peaceful or with limited combat. I have about 200 hours in Stardeus and I like how you can build out enormous spaceships (the spaceship map size seems a lot bigger than in Space Haven).

I do admit that Space Haven has nicer graphics.

I also play with almost no combat, as I treat Stardeus as more of a economic strategy and building game (e.g. highly efficient designs that also are aesthetically pleasing and not just a rectangle).

I am also actually curious about your question.