Rio changed them to white if I recall... pretty lame.
I’d go with the airflo poly leaders. They are clear.
I would not suggest a mono leader for your rage line.
These concepts are ALL about matching diameters. Suppleness also plays a major roll hear.
The tip of the rage is still THICK. It is a “power scandi” or a “finesse skagit” in all reality.
The poly leader or “Versi” leaders are also THICK at the rear. They match up nicely, plus the poly is a much closer match with the fly lines “suppleness”
The rage was designed for those types of leaders, and not so much for mono.
To transfer energy smoothly our lines must transition smoothly part to part (IE head to tip)
Your rods energy is going through from a thick rage head than suddenly Transferring to a much much thinner and stiffer section of mono, say 15ft 20lb tapered Mono leader will not transfer energy nearly as well.
This is not to say it can’t be done.
But your on the right track with the rage and a poly leader.
Those 12lb will be just fine, especially on the Klammy.
Stick with 10fters and keep 3-5ft 10lb maxima danglin off that, and you will be good to go
For a long time.
These leaders will also translate to true Scandi eventually, which will slowly bring you back full circle when your go back to mono and start building 18ft tapers!