I have quite a few mods, what I did is to set stack multiplier to 1, because I don't really want to increase the stack size, just the weight to fit more stuff into the rocket. Then I set weight ratio to 0.1, set items by name checkbox to disabled, added single item to the item name field, restarted, and nothing has changed for me. Did I perhaps misunderstood the configuration?
Yeah, settings for mod are confusing. Basically mod gets vanilla rocket capacity and multiplies it by the number you set, and about name part hope you use the guide to find right name for item to put in (I mean 3rd picture on information tab).