Without knowing how the back-end is coded, I don't know if this would work.
I'm wondering, if for campaign mode, there could be attributes that can be included in the JSON file for the following:
Scenario: Additional starting threat
Scenario: Additional starting hit points
Scenario: Additional cards starting in play
Deck (Hero): Additional hit points
Deck (Hero): Additional cards starting in play
I believe that, for the Rise of the Red Skull campaign, this would allow a user to create/edit JSON files to meet the rules