On Monday, June 4, 2018 at 11:37:14 AM UTC+1, Bert Coules wrote:
GB wrote:

It's not worth killing yourself over.

I agree wholeheartedly.

Maybe you'd be better off with some lighter weight wood...
Line the wood with DPM so it lasts longer?

I was thinking of plastic tarp or roofing felt. This was my original idea.
I can live with the need for extra bracing, and I've found wood (suitably
treated and/or clad) to be surprisingly resilient outdoors.

Thanks for the thoughts.

You might consider cement board, expensive though