I also don't like not having physical controls. You just gave me the idea to attach a simple, black rubber o-ring around the temp controls. I just want a guide for my finger. I'll start with something gentle like clear or black silicone sealant. Whatever won't damage the finish.
For switched power, there are power cables that disconnect when the battery voltage reaches a certain level. There are also separate devices sold that do this, but I've never looked for or seen a plug-and-play version. They were all components to be wired yourself. So with the requirements you gave, you're looking at buying or building a power cable that auto-disconnects based on battery voltage or timer or other condition.
For switched power, there are power cables that disconnect when the battery voltage reaches a certain level. There are also separate devices sold that do this, but I've never looked for or seen a plug-and-play version. They were all components to be wired yourself. So with the requirements you gave, you're looking at buying or building a power cable that auto-disconnects based on battery voltage or timer or other condition.