Here's a shot I posted a quite a few months ago showing my pump bypass kit installed. It fit just fine between the small inline filter on the left and the right-angle elbow (grey color), both of which were part of the camper's original fittings. Once installed, the brass valve stays in the line. To winterize, you attach a small hose (comes with the kit) to the valve, turn the valve to the bypass position and turn on the water pump. The small hose gets stuck into the jug of antifreeze and the pump sucks it out and pushes it into the larger water filter canister, then out through the faucets. Be sure to set the water heater to the bypass position or you'll end up filling it with AF. The part of the water system that gets antifreeze with this system is small, that's why you'll need less than a gallon. The cost savings will pay for the pump in one season.
It's never too late to have a happy childhood!
Lee, WU0V, and Courtenay, N0ZDT
2011 Rockwood A128
2000 Silverado 1500 pickup
60W solar system
2000W inverter generator