Dennis, there aren't any regulatory hurdles that would derail your project. As Ron stated, you can legally do ANY fabrication, modifications, repair and maintenance you wish without the Repairman's Certificate. The Repairman's Certificate is only needed to endorse the logbook following the Condition Inspection. If you can't get the certificate (I don't think you will have any problems getting it....) any A&P (AI not needed) can supervise the Condition Inspection and endorse the logbook. There are many A&P's who will work with you on this once they see you have an excellent knowledge of the aircraft.
Enjoy!