I'll answer the factory harness question.

Yes, I am using a modified stock harness and no, it was not hard to do..... The Gen III truck harnesses are easy to pull apart and modify, if you have the schematics from the factory service manual. Please note, I did not say Chiltons or Haynes or the like. What I am referring to is a set of Service Manuals from Helm. Alternately, a digital set is usually available on Ebay or an online subscription to Alldata will get you the pin-out information you need.