You might want to ask Camping World if dewinterizing is part of the winterizing package, or what they might charge to do it for you. My dealer includes it in the cost and then he pressure tests the entire system to make sure there are no leaks. Once you are more familiar with the coach you'll feel more comfortable about doing it yourself.
2013 Winnebago Aspect 27K
E450, V10, CRV, Blue Ox