In our 2015 CS3921 we had the powered incline w/ sleep number mattress. There was a small storage bin under the mattress - maybe 3-4 cubic feet. About 1/10th of what our '19 Ventana with a conventional mattress and non incline has.
I do not know anything about a loveseat at the foot of the bed, do you have a link to the video?
For our CS it was only the head of the bed that rose up, from horizontal it rose at least 45degrees (nice angle for viewing the TV). As it rose it pulled the foot of the bed toward the head of the bed since the mattress length doesn't change. I'd say the foot moved toward the head a good 6" giving more clearance to the rear wall (in our case the door to the garage).
Granted that was a '15 - they may have changed the bed mechanism in 4 years.
Richard & Denise
2019 VTDP 4310 K2
2019 Expedition, Nighthawk & AF1