Top marks for ingenuity. I have to suspect the brake test at your testing station if it can not cope with different vehicle weights. Would it fail the brakes on a really light car I wonder?
As for the EGR, without it for so long soot is bound to accumulate in the exhaust. The better solution is not to blow it out at high revs, but to burn it out by initiating high temperature regeneration, which the ECU normally takes care of but which I believe can also be done from a decent code reader.