Like nmrver, on my 37ND I use a 45 clear elbow. I have gone one step further and when not connected I added a clear straight connection which will catch and small dripping leaks from the gate valves. This prevents any surprise from happening when I remove the cap. Photo attached.
Also, when connecting at a campground I use a Y connector to connect the 2 drains into a single hose for the sewer connection. I have only stayed at one campground that had 2 sewer connections at the site.
http://www.amazon.com/Camco-39812-Rh.../dp/B002OUIXU8
I run a 10 foot hose off each drain into the Y and then a 10 or 20 foot from the Y to the sewer hookup.