GuywhoIdidn'tthinkwouldevertroll: I really think you're overthinking this. Do you have any troll control on the "Big Johnson"? I have it on my 90 Merc, and can reduce rpm's at idle by almost 300. At that I can maintain 1.2 easily (spinners/slow plugs). Have found that 2.5 to 3.5mph often works better with Shad Raps or Flicker Shads. I commonly use the bow motor to steer, and correct if needed with the big motor. Quit using bags of any kind while trolling with kids. Always getting hooked up one way or another. Still use one or two while drifting cross wise to wind with jigs instead of back trolling. I like long rods 8+ for out side plugs or planner boards, and intend to get a couple of shorties (5') for inboard. Much easier to deploy. Have you considered down riggers? Can be a blast under certain conditions. Easy to mount and use once you get used to them.
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"Need video of you wife being keel hauled deploying those drift bags".
HA HA Can't imagine that ever happening but would pay big money to see it if it ever did!