Did u get it fixed?
Hilo's are all different, but similar, so I will give you my camper issues.
The water line goes behind the fridge getting to sink, and later to shower. The issue is that the back of the fridge is basically outside, outside of the heated space anyway, so is in the compartment open to outside fresh air flow. That pipe will freeze there no matter how hot it is inside the coach.
In my shower area the pipes go under the shower pan before they get to the bathroom sink. This area is not open to air circulation inside, so will be nearly as cold as the outside air, and the floor is not insulated. Good idea to at least put a vent so there can be some warm air circulate under the shower, otherwise that part will always freeze. Remove the base board/wall panel under the shower to let it thaw.
Keep cabinet doors ALL OPEN during cold weather and keep heat going. I use electric heater since Im home and can plug in. I aim the ele heater at the cabinets to be sure that colder area gets plenty of heat. this is where the pipes are too.
My hot water heater has two by-pass valves. One you can see and the other is on the back side of the pipe, but is there. Both are right at the water heater. Turn those 90 degrees (only will go one way) and that will bypass the water heater. Drain the tank. Now when you blow air in it will not be going through the water tank. Issue there is that it is 6 gallons and will absorb the blast of air going through the pipes, and until the 6 gallon tank fully fills with pressurized air to the same pressure you are putting in then the downstream pipes will not evacuate the water as efficient.
The water heater is insulated, so you probably were safe and that did not freeze. If it was not a hard freeze then maybe the pipes are all fine, they can take a little bit of freezing, just not a hard, solid, all the way through freeze.
Pour the RV antifreeze down the sink drain and the shower drain also so those do not crack. Those pipes are bigger and the frozen water will expand more than as in the small feed pipes, and more likely to crack pipe.
The one-way valve will not let air/water go into the water tank from the city water fill connection, so nothing to worry about there. That valve is part of the water pump assembly.
Good idea to drain the water pump. You can try just pumping air from an empty water tank and this will remove some of it. There will be no way to remove the water between the pump and the city water fill incoming pipe T connection. Good enough for the South, but for hard winters I want all water out. i go in and remove both inlet and outlet pipes and run pump a few seconds to vacate it. The pump is not cooled by the water, so can run dry with no damage by the way…