Mobile ad-hoc sensor systems are employed increasingly for distributed tasks in unreliable conditions, such as terrain exploration and measuring. Here, self-organising solutions can help ensure reliability, availability and scalability, while making use of unreliable components (or agents) with limited resources. These enable agents to act independently, and to exchange and combine their partial solutions into a (more) complete result, which can be transmitted to users before all agents fail. In previous work, we have studied how foraging-inspired self-organisation can help mobile agents achieve a collaborative task -- terrain exploration and information gathering. Obtained results revealed two key aspects impacting success rates: the strategy for exploring as much uncharted terrain as fast as possible, and the strategy for encountering the highest number of agents that hold complementary information. In this paper, we explore further techniques for these aspects and introduce passive pheromone evaporation. Our results show that a hybrid approach improving exploration efficiency features higher success rates than basic stigmergy models, random exploration and Lévy walks.