I’ve moved a bunch of them. Remove the control box and open it up. Place it where you want it and then replace the cables with appropriate length cables. You will need 2ga welding cable, correct size cable lugs, heat shrink tubing, a lug crimper and split loom to protect the cables from chaffing. As Gnpenning stated you can change to an Albright Contactor switch, they are smaller, it’s just a bit more work. What ever you decide, do not use starter solenoids, they are not rated for enough duty cycle.
For example mine is mounted to the frame behind the grill and radiator.