Handbasket and Dave - thanks - will upgrade lights. And Handbasket's comment suggests that the idling is in any event not doing what I thought it would do (i.e. maintaining the juice in the house batteries).
This unit (new to us) does have 2 new house batteries. I think my first move should be to get a sense of how much power I do have on board without plugging in. I can do this by actually experiencing it on our first long road trip. Or perhaps invest in a trial in my driveway without being plugged in and leaving lights on until bedtime and then leave the furnace on for one night. For the cost of the propane for one night I will then be better informed.
Thank you all.