I did not read everyone's post. If this is a repeat comment, well ... sorry.
You are perfectly fine. You can leave the "pink stuff" in the lines or drain it with you low point drains, or .... even if you want ... you can sill blow out the lines with air. Once the water is replaced with "pink", your lines are protected.
Pink Stuff does not expand, but it does jell up when it reaches a certain temperature below freezing (water temperature). So, it really does not matter if you leave it, or drain it. The water is gone.
You will want to rinse your system very well in the spring to get all the "pink" out. If you have foamy water, you just need to keep flushing clean water through.
About your water heater? Without a bypass, you had no choice. There's nothing wring there with what you did. You'll just need to rinse it in the spring.
About opening the low-point drains. After I run the "pink", I open mine last to let the pink drain. I like the idea of having all pressure off the lines. It just make me feel better.
Rest easy and enjoy your winter. Think about Spring coming and new camping adventures. It will help keep you 'energized' through the long winter months!
