You can turn them off in world generation, no mod needed, for what it's worth.
I have the same trepidation in DSP, and I'm hoping they at least take the same tack as Factorio and allow enemies to be turned off entirely. While there is a little bit of fun in trying to design self-sustaining defense lines in Factorio, I never found that enjoyment worth the effort of having to clear out the enemies to build ever-larger factories.
Well, except for Clusterio Gridlock event. In that event, given that you were starting the map with 40x mining productivity and similar bonuses, and were playing with 100+ other people, giving you awkward map layouts with high enemy growth was just about the only way to make it interesting.
You're penalized for building big dyson spheres (and even more penalized if you have graphics turned on for them).
You're penalized for building on more planets/system (and rewarded for cleaning up old structures, even if they're no longer actually doing anything).
I hope the combat patch comes with a lot of performance enhancements for existing content...
Uh...you've been able to play Factorio in a peaceful mode without a mod for years. It's just a checkbox when you're creating your world.
And I imagine when DSP gets the combat update, it'll have the same checkbox.