The flat-mount on my Cedar Creek has 2 allen set screws, (one on each side) that can be reached with the supplied reeeeally long allen wrench or an allen\socket with a long 3/8" extension. If you can't see back there, try using a flashlight and mirror. That's how i first found mine. Good luck.
2010 Cedar Creek 5th Wheel 34SATS "The Beast"
2006 Ford F350 Lariat 6.0L Diesel
2003 Harley Heritage Softail "Hogzilla"
1988 Harley Softail Custom "The Fireman"
1986 Marriage to "Wifey" (patience of a saint)