No cutting down of the tubes is required...the 9mm long tube in the mating kit (at 9mm I guess it is really a "ring" not a tube) is used between the two couplers--or between a TRP and a coupler if space constrained. Depending on the thickness of the divider panel you might be able to leave the flange on the ring. If not it is only 1mm thick plastic and could be easily and quickly removed--probably a 10 minute job--and since it is not seen it doesn't matter how it looks after you hacked off the flange. The ring would also be an excellent template for locating and drilling the holes thru your case divider panel.
Here is what the mating kit ring looks like. The kit will likely be at or about $10, (I still don't know costs yet so that is only an estimate) and will also include a second ring that is solid in the center for those who want to divide a reservoir into two reservoirs.
I am not pushing you that way of course--just making sure you know all of your options so you have the best chance of success =)