I'm heading out to my camper in a few days to complete a few things I forgot to grab when I initially stored it, I don't want my tools in there all winter (some have batteries, etc). Plus I just need an excuse to go see 'her' again anyway. I'll document the low point drain deal with pics or a video. In my model, the valves are also in the bathroom cabinet under the sink. I completely forgot about that part of the system so I have to go back and correct that anyway, so I'll try to remember to take some pics. It sounds like you found the correct valves, but I'm not sure if you actually opened them, they aren't like the valves on your water heater. Next time you open them, have your water pump on. It helps to have 2 people for this... one outside confirming the antifreeze is coming out, and you inside to turn the valves off again once that has happened If nothing comes out at all and your water system is pressurized, it doesn't sound like the valves are actually open. I also picked up a small hand pump so I can manually pump antifreeze into the system from outside the camper. Should come in handy for the black tank flush and city water connection.
2016 27BHS Elite
2012 F-150 EcoBoost / Max Tow (Sale Pending)
2017 F-250 Lariat (Factory Ordered on 4/20)