I am not familiar with your new rig. But looking at this brochure http://www.uvsconsole.com/manager/ad...1886951155.pdf
, it looks like the pull handles for your sewer are inside that panel, but the actual sewer hose connection is not. If your "wide pipe" sewer line is below that side panel and toward the back (as shown in the brochure) then that is where you hook up the sewer hose to drain the tanks.
As for the hole in the bottom of said side panel, it is probably for your fresh water supply hose to connect to the inlet to the camper which seems to be depicted on page 9 of the brochure and just below the filter canister.
It's merely an hypothesis.