I only got the jog control to work right once. No one could ever give me a sure way to get repeatable results with it. Again, mine could have been that one out of a thousand that was cursed from the beginning. You can always put the 3rd battery in a rear compartment if your boat has one. Or do what my buddy did for years in his boat by using a pair of dual purpose batteries like a pair of Walmart group 29's and use one of the batteries to crank the big motor and run electronics. Just make sure that battery doesn't have the jumper on the terminal where the ground is for big motor and electronics if you go that routeYes using one of the trolling batteries to crank the big motor and run electronics can be risky but I don't think he ever had any issues and he was cranking an old Johnson GT150 V6. You know how bitchy those motors can be for no good reasonOne wrong move in the VERY SPECIFIC starting process both cold and warm and you're in for a bad time. If your motor is as sure to start as you say it is I don't see it being an issue. For shaft length keep in mind that steering collar will take up about 6" of shaft length so 45" should be about right for you. Other than that you'll love having spot lock. I won't be without it again. Nothing like taking as long as you need to rig up correctly and the boat be exactly where you left it when you get back on the trolling motor.