Congratulations on the new fun toy. We had a 1990 Bounder 27D with twin beds and absolutely loved it and it was very reliable. The biggest problem we had was with the plastic parts, tail light bezel, dash AC/Heater control bezel. moldings, even the bezel around the old analog, tube type CRT boat anchors. Just found work arounds.
I had a similar problem with the lights on a pickup truck years ago and while I don't think all electrical problems are caused by bad grounds it does sound suspiciously like a missing ground. Lights not coming on but causing dimming is often a ground problem caused by the lights trying to find a ground back through the filaments of other light bulbs.
I hope the solutions are simple and trouble shooting very easy so you can get on the road and in a campground.
