Thanks Robin. The aluminium sections sound a great idea.?Having heaved several 4.5m+ lengths of 220mm X 45mm timber up there in the last few weeks these would be a doddle.
What I want to do is play around with the 2 or 3 sections (each of several boards) trying various heights and location. I've got a couple of steel trestles and can probably borrow some more. Once I've decided on a config I may make timber supports.
John