OK3wire, you could purchase something like the Camco 39463 Sewer Cap with Hose Connection and use a small garden hose (not fresh water hose) to drain the grey water from your Roo to your Barker.
It may take a bit longer, but it is much easier when dealing with elevation issues.
2013 Rockwood Roo 23ss
2012 F150 Ecoboost
Camped for 12 nights in 2015 - too many cancellations
Camped for 25 nights in 2014!
Camped for 24 nights in 2013!