8020 or a similar extrusion can be mounted a number of ways to give you extensions. I recently made up a batch from 1-1/2" profiles with 1/2" MDF 2" wide on 2 sides, one edge is flush and the other edge proud by 1/2" so I can cut on them.
I use a bench dog with a carriage bolt and knob to attache them from underneath the MFT. This allows you to cantilever them pretty far and still ahve the entire top open to clamp to. The top t-slot fits the Festool clamps. Here are a few photos:
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You can also rig them up without the MDF and keep the top flush to the MFT top and just extend them out from the side rail, using another chuck as a leg. The great thing about this stuff is you can bolt it together, take it apart & reuse it over in many different configurations.
RMW