Okay here's my idea: Vehicles with Defusal can drive over mines to detonate them WITHOUT damage to the hull. But, with or without Defusal, running over mines adds a large amount of heat. If a driver runs over more than a few mines, he will overheat. This will allow mines to remain an effective obstacle while still allowing for large-scale clearance in action. Alternative: my other idea: tanks take a percentage damage from mines with Defusal on. Depending on results, both effects could be combined together.