Jhsgls,
Can't help with right size mattress - yes it is an 'RV King', but we got a mattress topper for the short queen in our hurricane from CW that has made a world of difference...
Higher price now than when I bought - but this is a link to the king version:
Perfect Harmony Mattress Topper - RV King - Carpenter 31374542247 - Bed Pads & Mattresses - Camping World
Jamie,
What foam/thickness did you use for the drop down bunk? Not sure if the Axis has a deeper spot there - Hurricane doesn't allow for much thickness when the bed is retracted. As we recently found ourselves trying to use it with 2 bad air mattresses on board - something not able to leak is sounding good...