No...you don't really need a designated hose. But as a practical matter and in the interest of safe sanitation it is highly recommended. It's not the distance to the ports but your handling of the connections that will cross contaminate things. Bottom line: Use separate hoses.
Personally I carry four hoses. 2 - 10 ft and 1 25 ft white drinking water hose. And one 25 ft green standard garden hose. The white hoses are for fresh water supply. The green one is for everything else. Including black water tank flushing.
Chuck - Sparta, TN
2012 Jay Flight 22FB, 2 x Honda EU2000i
2013 GMC Yukon XL Denali AWD
EDUCATION is what you get when you read the fine print.....
EXPERIENCE is what you get when you don't.