Mission planner would be a spread sheet like mod.
It would request all available missions and categorize them.
You would be able to apply filters and ordering so you better plan them.
Example: if I am interested in earning 2x xp, I would apply filters to them, so I would apply a filter in the game so it would show the tanks that have this mission. Otherwise, I am planning for equipment, I would filter them so, to find them, and use a button to filter tanks that have those kind of missions.