Purchasing a tool or building a jig to fix a design problem that should not exist makes it clear the original design is crap. Even if you get them perfectly aligned you still have the dimpling issue. Poor design all the way around. Instead of making radios, coolers, socket sets, rulers, sand paper (for hand sanding) and various other gadgets spend some time of a new rail connection system.
I have both Festool and Mafell saws, rails and connectors. The Mafell is a better saw with a better rail system and connector and it works on Festool rails if you have those. The upsides are the connector which stores on the rail, the anti-splinter guard design, and the cord deflectors that are included with each rail. The only downside to the Mafell rails is they are not as heavy duty as the Festool rails. That is not to say they are fragile, but just not as rigid as the Festool rails. I'd prefer a little more mass on the Mafell rails, but that is just me. My first tracksaw was a TS55 and I later purchased at TS75 for the extra cutting depth. After trying out an MT55 I sold the TS55 and kept the TS75 though I use the MT55 and it's rails almost exclusively. I'll also add that I purchased the 120" rail to avoid using connectors and have enough other sizes to never have to use the Festool connectors. I have parted with some of the Festool rails, but kept a few rails including the 120" for use with the TS75. If Mafell enters the market with a TS75 equivalent I'll sell of the TS75 of the rails.
Like others have mentioned the 120" rail is for the most part an in shop rail only. It is too big to carry around a job site where it could get banged up or bent.