Ours is not the deluxe model, but the mattress is still challenging as it is. I like a foam topper and a mattress pad, so I simply (not so simple, really) wrapped the mattress pad around the foam topper, since it is nearly impossible to tuck anything around the existing cushions. Then I wrapped the fitted queen sheet around the pad and mattress topper with an unfitted sheet tucked in the bottom (feet end). It's a little lumpy, but we're camping, right?
Sleeping from port to starboard, we still don't have enough foot room, but we make it do and my husband is 6'3".
Scamp says it's a queen mattress, but we figured out it is a queen only if you raise up the side (front end - sofa end) with those supports. But then how do you get in and out of bed when you need the lav at night? We thought we'd have a step stool in place - but there is no room for that. So we sacrifice foot room in order to sleep port to starboard and we're okay with that.