We just got our 195 4 days ago and replaced the short Queen with a full size 10” thick Zinus foam mattress. We spent 1 night in the rig with the new mattress, and it is a bit of a squeeze an the TV side. Our new mattress has a removable cover which can allow us to trim the end of the mattress to give a bit more clearance, and zip the cover back over it. I think we will go ahead and trim it by 2”.
We have the original 3/8” plywood top for the under bed storage. The extra overhang with the full length queen isn’t noticeable unless you try to sit on the edge of the mattress. BTW, we found it necessary to reinforce the plywood top with 2x2 wood braces on its underside because the first time we sat over the lid, the screws in the middle hinge pulled out.
Hope this helps.