Replacing wiring harness

I have an older Lazer HP 48" with 21hp Kawasaki.
Model- LHP4821ka
SN - 279100

I had some problems with the seat safety switch and PTO switch so I jumpered the connectors. Well last night I guess the jumpered PTO connector caused a small fire and melted part of my PTO connector and some of the wiring around the PTO connector. (Yes, I know I shouldn't have jumpered the different connectors but I needed my lawnmower...lesson learned obviously)

So I'm thinking I might replace the harness. Has anyone ever had to replace the entire wiring harness? How hard of a job is it? Any tips or advice would be greatly appreciated. Thanks in advance!