I see your point, With My WITECH , I monitored that thermocouple pass the EGR Vale and Exchanger with infrared gun, it was still 200-300F.
The bypass valve does NOT stop the Heat/Gases. I even cap the Plenum and made My own tube from EGR Valve to atmosphere. It still triggered rationale codes. Keith GDE mentioned what you are doing the SCR/DPF and I agree 100%. if you keep messing with the EGR W/O tuning or capping it ( Capping it still will cause problems W/O Tuning) . You must delete or Hope Keith can work on road CAA COC tuning that will extend the life of the entire system that is so plagued with problems.
If you have 2014-16 Ecodiesel run lower concentrate of Urea Mix 50% DEF / 50% Distilled Water to eliminate DEF Injector/pump crystallization.
Another ratio 2.5 Gallons DEF to 1 Gallon DS.