It takes a little practice to learn to quickly position a 55" (1400mm) guide rail when making a 48" cross-cut with a TS55,
Trust me, hundreds of thousands of Festool owners do this routinely.
My suggestion is to place an index mark on your rail as soon as you find the magic place to start the cut. My other suggestion is to use the clamps to hold the guide rail in place when making such long cross-cuts. Actually, it is policy in my cabinet shop that the rails always be clamped. None of my employees disagree. The few seconds it takes to set the clamps is well worth the effort. If we were to miss-cut not only would we have spoiled raw material, we waste time. Even our basic pre-finished maple plywood has value. Some of the exotic veneer plywood we use costs more wholesale than a TS55REQ.