Looking on line, you appear to have the 22MKSE "Special Edition." Non-special ones seem to have a full-time queen bed and no sofa.
If the back of the sofa becomes the bottom half of the bed, I'm guessing you may have to make some "legs" to support the end of the bed (i.e., top of the back of the sofa) when it's folded down. And I'm assuming that the part of the back of the sofa that matches up with the permanent part of the bed is at the same height as the permanent bed. If it's not, you'll also have to do something to raise/lower the back of the sofa when it's folded down.
1988 Coleman Sequoia - popup (1987-2009) - outlasted 3 Dodge Grand Caravans!
2012 Roo19 - hybrid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado 1500 Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10