First decent trip and pretty surprised at the mileage...

Check your voltage at your headlights with them turned ON. This will give you an idea of whether or not you have a wiring problem or just old worn out bulb filaments. My Monaco came with headlights from a BMW 700 series Autobahn cruiser and the headlights are more than adequate for a MH. A lot of the newer coaches also come with headlight assemblies from an automobile or pick-up truck so if the voltage is sufficient the lights will be fine, if properly aimed, of course.