FWIW, it’s unlikely you’ll need the rear locking diff. Land Rover traction control is black magic.
My wife drives a RRSC, locking rear diff. Most extreme “off roading” it’s done was a soaked clay road at the gun range.
My dad had an LR4, locking rear diff, don’t know it ever went down a dirt road.
I have an LR3, no locking diff, and beat the piss out of it regularly in a 500k acre national forest. It has been sunk in mud over the tops of the tires, crawled up 2’ almost vertical ledges, many creek crossings, etc. I have not gotten it stuck yet. Been through places where a buddy got his Land Cruiser stuck. Closest I’ve been was high centered in ruts, likely made by 37’s, I’m on 32’s. Air suspension went into extended mode, I hit the switch to raise it higher, and was able to back out.
People seek out these rear lockers to drive down fire roads and it’s just not necessary.