bulgogi......you really need a fuse on the power wire at the back battery also. You should have a power lead going from the alternator to the isolator and then a lead with a fuse going to the front battery and then another lead with a fuse on the rear battery. Both battery fuses should be close to the battery.
The purpose for the fuse on the battery positive line is not to protect your electronics it is to protect your car. If there is a unfused power line running front to rear and the car is in accident it is very possible the car will catch on fire. If the power wire is shorted to ground the car will defiently catch on fire. You have a nice car I would hate to see that happen.