Resto, Repairs, and adventures with 'Peggy' The 1997 90 Pick-Up

I got her a couple of weeks back, and love the way she drives, heats up quickly and works so well off road in my woods. But prefer my Series 3 doors with the sliding windows, winding the window is like trying to scratch my big toe while driving and opening the passenger window for the small dog
from the driver seat got me tempted to make it electric.
My first problem has been nasty wiring possibly caused by a rear 1/4 chassis replacement.
The brake lights came on after a power wash under to clean up the chassis, pre needle descale.
I knew there would be hidden work, but hey that's all part of the package.


So the purple always powered cable for a 12S Socket or other toys had rubbed and shorted through the brakes.
Some time later after pulling through what was left from previous repairs and multiple joins, some good some not so, and removal of no longer sticky hard old electrical tape. I began a journey into the colourful land of landy wiring; repaired the baddest bits and found a tight bunch of bullet connectors, just inside the chassis where all had been cut in one go, then patched back together .
So I got a new back harness from Autosparks, who make new ones up in Nottingham. Being the 90 Pick-Up it's a more reasonable price than for many models with heated rear window, rear wiper ect.

It really is like for like, I'll probably add a few wires for whatever, and since I have vinyl loom tape, wrap over the new loom again.
The question that's got me; 'to fit inside or run outside the chassis', which I will be removing some plates welded over old holes, rust has crept beyond them.
I will cut out the bad and replace it with new metal, so there are no plates over anything, just one sheet of metal, all one thickness. I will use my plasma cutter to cut out and have a pattern all in one go, make a card template to cut new, flat, metal and form to the removed part so it should be a perfect fit.
Would it be best to leave the loom external to the chassis, or put it back inside again, where there may be some jagged bits of old rust and edges to chew away at the shiny new harness ??

Got this Manual which is very comprehensive, and just covers the 300 TDI Defenders for the three years.
It suggests both with and without CAT downpipes were fitted.



Would it have only been the wolf defender that there was no catalytic converter fitted, or which civilian vehicles may have had no cat.
I only ask as many fit cheap decat pipes, and I would imagine this would cause an MOT fail, also possibly a £2500 fine as it's a commercial vehicle for which the penalty is greater.

The flexible part of my pipe and mid section are showing their age, and I’m considering the best options.