The way I look at it, the effective resistance/drag caused by the alternator is directly proportional to the current we need to run electronics/charging system on truck. Does anybody know how much juice the electronics pull at idle/wot? Turning off all possible electrical draws (drl, headlights, cab light, hvac heated heats…etc) and making sure your batterie(s) are fully charged would make the draw minimal as possible.
If this proved effective, someone could try a way to use an electric clutch, like on the a/c compressor, and install them on the alternator(s), then wire a switch/button to disengage clutch…isn’t that how gm fixed the alternator belt squeak?
Also, If you were able to "un-excite" the field winding of the alternator you could also effective remove the electrical charge drag, but you would still be rotating the shaft of alternator and to my knowledge, most current production alternators are self-exiting.
Either way would be neat experiment. However I personally feel it’s not worth that much power with respect to how much these trucks are capable of when mildly tuned.
$.02
Bill.