Thanks again for all the replies.
Your right that a scaffold structure erected on private land for private use (and no employees help build or climb it, apart from the owner) does not fall under the HSE's or WAHR regulations.
I would have thought 'due diligence' with regards to those under and around him during construction needs to be shown though.
If the owner could prove competency and experience of erecting Independent Tied Scaffold, would he also be viewed as competent at construction if following a 'model'.
Visible disclaimers would need to be displayed so that people could not climb the structure, and use of barriers around the structure, before and after construction, and during 'display'.
Yes the weight and stability is a serious consideration, especially on wet ground.
Apart from the rain, I'm sure many would try and pour cold water on it, but if thought through don't see why its not possible.