I'll try and get a photo of where my handbrake light is on my dash. There could be a possibility though that our dashes are not the same set-up. Will post photo tomorrow.
As well, your 'joining' of your heater hoses, may not be the best fix. At some point, especially when you're planning your first long distance trip, I'd go ahead and buy enough heater hose length and replace it all. For my 345, Keyair has said that I need about 70 feet, what with the Auxiliary heater in dinette seating area and the motor assist on the water heater. Good luck, Derek