Our Designer 5er has the same problem - lots of space under the J-steel, but no opening in front to use it. We have a lot of other space available, but, if needed, we raise the bed part of the J-steel to a 45 degree angle, and hold it up while squeezing the stuff into the space. Incidentally, the way this sofa is upholstered, there is no way to make a front opening without removing the fabric.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.