I also tie-wrapped a piece of old wetsuit over the plate, since I dive with a 2mm shorty sometimes.
This is exactly what I was thinking. When I see people selling $40+ pads for a backplate to make it more comfortable, I keep on wondering why should it cost that much and I thought of using parts of the neoprene from a wet suit. I just posted a thread in the BC forum asking about this.
Great idea. I also wondered why a STA costs so much. This is a much cheaper alternative. Maybe you should go into business selling PVC STAs.
Personally I dont like duct tape holding my gear together. Dive Rite makes professional looking products, that have been designed and tested by divers, and are supported by a professional company. People are willing to pay for that quality.