Mark a campaign as "Seed" and put example ideas in it that are generic and intended to be copied into new campaigns to seed the activity and avoid empty party appearance.
When creating a new campaign, have an option to clone the ideas, moving them to the new campaign, including all comments and votes, but NO FOLLOWS so that the contributors don't get notifications on their sample ideas.
Stretch Goal: Create fake user accounts in that seed campaign and mark them as such. Make them co-submitters to ideas and migrate them to new campaigns, too.
REVERSION: When the campaign reaches critical mass of activity, have a feature that sweeps through and Archives all of these provisional seed ideas (and see people).