Greetings, when insulating it, you do not need to change the rectifier bridge, so it is isolated, so as not to have to change anything, now, with respect to changing the polarity, you have to take into account the accessories and electrovalves or solenoid that the machine has, for giving you an example, once they called me for a problem of a machinery that I did not want box), check it and detect that they had put the battery to the setback, that is, positive to mass and negative to the alternator, the same was damaged by the alternator, inverted the polarity of the battery again and ready, I release the machimbre, conclusion, the solenoid has polarity.
By this I want to tell you that first look what accessories you can burn when the polarity invests, such as reproductive radios, some electrovalvulas work the same if you invest polarity, others do not, which you can solve by investing the connection of it. The bulbs no matter polarity, they still light. With the tractor I don't think there is a problem of investing polarity except for that solenoid if you have it. Check and test with caution if you are going to invest the polarity, because the safest thing is also that the engine's direction is invested, due to the effect of the start. I miss that the machinery that repaires light without problems with the invertity battery .. I hope it helps you in something my experience. Greetings.