Actually we have three points, hot cold, and fresh water. There is probably another on the OPs trailer; it is pretty important to find it before winterizing.
I opened mine up a few weeks ago because I was not able to schedule any camping time and want to lower the risk of any bacteria having too much fun, making the system stinky.
Drain the system for extended periods, but especially for winterizing.
2011 PrimeTime Tracer 2600rls
2001 GMC Yukon XL 2500, 6.0L 4.10:1 axle ratio
Nights camping 2014 - 17
2013 - 15