[Eric O]

Back when 177 used 80/20, we used to tension axles by actually welding threaded rod onto a slider nut that our bearing block was mounted to and the sliding the whole thing down the slot. You then just put a washer and nut on the rod at the end of the extrusion and tighten down. It’s a similar concept to what you have here, but less complex, and you don't depend on the friction of the slider nuts keep things from sliding. There are a few limitations by doing this. You can’t mount anything from the end to the block, and have to leave some space at the end of the extrusion for the rod to stick out (crucial for fitting in box when doing this on a drive base).