Jeff, knowing you shoot the Viper, i was going to recommend what killadoe said...

when i first put on my Viper, that was my first thought was IF i ever got into HC 3d, i could easily swap the housing out....shoot some light line cutters for 3d and shoot my heavy arrows for hunting...

doubt its much cheaper than buying the WHOLE sight, but it will be true each time you put it on..and both will be ready to go, and you can keep your 5 pins on your hunting sights and keep 4 on the HC(think HC is 4pin max) i think it would be a good route to go.

trying to learn to do what your saying will be tough...if you shoot alot of one and not alot of other, you may confuse yourself in the heat of the moment...i know i dont THINK use my 20yd pin in the treestand...i know to throw my top green pin on it...also, might not work period...i could see the difference falling in the pin gaps...you would have to shoot each pin with both arrows and see and remember what pin is good for what yardage....