My SIP tablesaw also has a rear rail for the fence, but it didn't stop my having an outfeed table. I already had a large flat-topped bench topped with "worktop", so I arranged the height of the saw and bench to be the same, and dead level. The bench sits across the back of the saw, like the top of a letter T. I then routed a groove across the bench to accommodate the mitre guide and cross-cut sled.
Although there has to be a small gap between bench and saw, it still works perfectly as an outfeed support. And since an Xcalibur must weigh at least as much as my saw, I guess it isn't on wheels :wink: .
This set-up allows me to use the whole bench as support when needed (sheet materials) but other times (ripping 4x2 etc) I only need keep the area to the back of the blade clear. Hope this helps.
Colin