***Disclaimer: I'm not an expert, more of a hack really
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***
With that said, I do notice a few things in your plan:
My main concern is wether or not you'll be overloading the battery charge regulator. There's nothing in the manual that says what the capacity is, other than it supplies a battery that requires 1.8amps charging current. You may be fine, or you may find the battery drains way faster than it can charge. Maybe someone else has some input on this, otherwise you'll just have to do your own testing.
I would not put a voltage regulator in front of the battery. Your battery won't properly charge this way as the voltage supplied to it will be limited to 12V. The battery should have the full 14.7V coming from the electric start plug (red/green wire), so run that straight to the battery. Your 12V regular can be put between the battery and your accessories (presumably for clean supply to your LEDs).
I don't think your anti reverse diode is necessary, there's nothing behind the red/green wire that will draw power from your battery.
The relay is interesting. Having your entire accessories circuit switched on/off from the DC PWR plug effectively means accessories will only function when the sled is running (DC PWR plug is switched on via the sleds chassis relay, controlled by the ECU).
Hope that helps a bit, good luck!