A small improvement during the design stage would have made the MDF base and replacements unnecessary. Simply design the clamping force to be applied at the far end of the extrusion instead of from the top to the stock, and the base can be dispensed with.
If I had one of these taper jigs, I'd fashion a clamp myself, install it to the extrusion slots, and use the jig without any MDF base. One doesn't need the mdf to prevent tear-outs. That's what a ZC throat plate on the table saw is for.