YES THE NOISE CAN BE DISENGAGED...Tiffin just isn't going to tell you how to defeat a "safety feature."
I have a 2012 QBA but the alarm is probably in a similar location...
Mine was on the right side of the steering wheel behind the flexible ducts. Turn the key so the alarm is on and that will help you find it. CUT THE RED WIRE AND NOISE IS GONE. Make sure to tape or cap the red wire once cut. Did it on my old winnebago too.
Really bad design that forces you to listen to it every time you want to let a slide in or out or the shades up and down....
They should have tied it into the brake (wouldn't be that difficult) so when you press the brake the alarm goes off. Because you have to press the brake before putting it into gear.