I've had water problems in the cabover several times. I had removed the vent there and reinstalled with lots of dicor and eternabond. Then last summer it dripped right on me in bed in the middle of the night. I had the ceiling open at a joining of the ceiling sheets there from last time and it was pretty clear the leak had to be at the seam on the roof between the metal roof and the plastic front of the cabover. Though that seam looked well sealed I removed all its caulking, finding cracks in it, and replaced it with new dicor lap sealant. Then I put a four inch wide strip of eternabond over the whole seam. I am confident it is fixed now.
I really enjoy our little motorhome. I worked hard to fully understand how it all works and am confident I can take care of the house, though I have no intention of dealing with engine or brake problems should they arise. The first step is the electric system. A voltmeter is essential. If relying on battery power one needs to know how it s charging for starters. There is a voltage chart showing that a battery left without any charging is fully charged if over 12.6 volts, half charged at 12.0. After any charging from AC power or engine alternator and the voltage is artificially high for hours. Going below half charge damages the batteries (yes, even deep cycle ones, though not AGMs). Many of us have killed batteries learning this lesson.
Best of luck to you! On this forum we all enjoy helping so don't hesitate to ask questions.