Festool packs the longer guide rails, including the 2700mm, in sturdy purpose-built crates. All of the many rails I own were purchased from my primary local dealer. I have seen pallets of stuff from Festool at my dealer waiting being inventoried, but those are not long enough to contain even the 1900mm rails. I have been told that Festool bundles several longer rails for shipment, so the combined crates support one another.

I do own a 27oomm rail, because that is the longest which will effectively fit in the smaller shop room at my condo. Yes, with some practice the 2700mm rail is just barely long enough to rip 8' so long as you use a TS55. The base of the TS75 is enough longer that you need nearly all of the 3000mm rail to make the same cut.

Personally I had to wait until early 2009, when I bought a pick-up truck with a lumber rack, before I could transport long rails. Knowing in my larger condo work room I had space for a 3000mm rail, I bought that the same day as my 2700mm rail.

Previously I had bought the 95" 2424mm "Holy" rail, which could be squeezed into my Grand Am, unfortunately without its Festool crate. We discovered this the day in 2006 I bought it. My dealer saved the crate for me so the following day a good friend with a pick-up could bring the crate to my condo. Bummer that the 95" Holy rail is 11" too short to be useful ripping 8'  There must be a valid reason why the 3000mm rail is not offered with the milled holes to register the holes spaced 32mm. It could be that the LR32 holes are made on a jig borer of milling machine unable to hold a longer rail. These days that should not be a problem. My own Weeke CNC nested routers can handle 5' x 12' sheets. I do not allow any metal working in my wood shop, where those Weeke CNC routers are located because I do not want metal chips there. However, several of my friends in the metal working business use the same model Weeke CNC routers effectively. Compared to modern metal production CNC machines, the Weeke are inexpensive and yet very reliable.

It's not a matter of whether you own a Kapex or not, but how accurately you could make the cut. The accuracy of the trimming cut needs to be proportional to ratio between the width of the rail to the length of the rail. The longer the rail, the more critical the accuracy of the cut must be. It is not a matter of making a 30-second cut and calling it good. It's a calibration process that could require a tolerance (depending on personal preference) down to a couple thousandths of a degree.

On the other hand, as long as you used the same accurate saw t cut all of your rail's right and left ends, then it is less critical that they are exact, as long as they are consistent. One error would cancel the other.

+1 

You also need to think about the longest diagonal you might want to cut on a sheet of ply, plus someday having the 75 rather than the 55. IIRC, when I calculated it, that meant you needed 2900mm.