I am in the same boat, got the skyline aurora and their memory foam mattress last week, but they say you can not leave the mattress up top when closing the roof as it is too thick for the low profile aurora. Problem is, the mattress is huge and does not roll up easily as well as not being particularly comfortable, so it is going back.
I have looked everywhere for something to fit, from the vango california mattress (100cm wide 5cm thick) that some people say will fit with roof down, through to exped synmat duo lw (130cm wide 7.5cm thick) that even if it will not stay up there deflated, packs up small enough not to be a problem finding space for it. Exped do a non insulated duo mattress a bit cheaper that may be just as good for the warm environment of a van.
The Exped mats are very expensive but considering the 'memory' foam mattress from skyline is £80, at least it will be comfortable.