the best way in my opinion is to run a 6 GA. positive fused or breaker at the source in the engine compartment and a continuous duty solenoid rated for 100A minimum in the engine compartment either activated by something in the fuse panel when you start the vehicle or toggle switch the toggle will be low current just activating the solenoid and run the 6 GA on the drivers side so it cant touch the exhaust under the car inside of grey plastic pvc flexible conduit that that they use in houses or trailers HOME DEPOT has it and heavy zip ties its cheap for protection then a hole in the floor where ever the inverter and battery is mounted also put a short 6 GA or bigger from the engine or trans to the body and 6 GA ground from the AGM to body unless you run another 6 GA neg all the way up front to the block or to the battery if its easier but the main thing is if you use the body for ground you have to beef up the ground up front or it may try finding ground elsewhere because if the agm is low you will have like 40 amps charging it ,put the AGM as close to the inverter as possible probably $300 if you have the inverter already to do it right though im thinking $160 ish just for the battery and make sure its a deep cycle so it will last ,you could put the solenoid on the inverter side of the positive feed but I would rather it not be inside the cabin, just make sure its fused on the positive side close to the source and on the AGM side of the 6GA no fuse on ground,so fuses on both ends of the positive 6GA probably 75 or 100A
