Good idea, John!
I only learned last year that a lot of greenhouse plants like toms, peppers etc, really only want lots of light, and not necesarilly heat, so an upwards structure, maybe with some shading against the scorch you mention, may be the trick!
We shade using debris netting, held on to the aluminium roof bars with clothes pegs, and while you may need a stronger fixing (you will), there should be a 2 West and Elliots solution somewhere...
Don't move though, Val's right as usual!