all of that should be under the kitchen sink....it is in my 2017 WH. The only diff may be that you have a two valve bypass and not a three, but that's easy to figure with the google image search. dont' forget to drain the HW tank. I open everything up at the sinks, outdoor shower, under trailer drain valves etc. and use light air pressure from a portable compressor using a homemade connector to the city water hookup.....clears all quickly and well. Your trailer may or may not have the black tank rinse connection with it's own hose connection....if it does, there's a check valve in its circuit made of plastic...I don't recommend air pressure for that, but DO pour a quart of antifreeze into through the hose connection (remove the cone mesh filter and use a funnel). one cup of antifreeze into every P trap. if you're a suspenders and belt person, the the intake hose at the pump will let you put as much antifreeze into the cleared out water lines as you want.
Experience is what you get when you don't get what you want.
"We'll be friends until we're old and senile,....then we'll be new friends."