This paper explores completion of a network of ‘high occupancy or toll’ (HOT) lanes on a highway system, parts of which had no available right-of-way for additional lanes. The explored solution would convert some, but not all, general-purpose lanes into HOTTER (‘High Occupancy, Transit, or Toll on Existing lanes with Rewards’) lanes. Some users would switch to high occupancy travel, some would pay tolls that would vary depending on the travel demand, and some would stay in the remaining general-purpose lanes. HOV3+ would go for free on the HOTTER lanes. Tolls collected would be dedicated to incentivizing enough people to travel as passengers. The operating objectives would be that the remaining general-purpose lanes would experience no service degradation from the change, the HOTTER lanes would offer congestion free travel to HOV3+, transit, and toll payers, and no external funding would be required. A sketch-level evaluation was carried out. Key challenges included: estimating how much temporal demand-shift would occur as the free HOV3+ would travel at their preferred time rather than the time that the congestion had previously forced them to travel; relating morning peak traffic volumes and patterns to the evening peak; estimating the value travelers would put on time savings in the HOTTER lanes; estimating the toll rates; and determining how much incentive payment would be needed. The sketch evaluation found that the operating objectives could be achieved while reducing emissions and generating a sizeable annual surplus, even after payment of operating costs and incentives. Deeper evaluation is recommended.