I decided to edge the half-half tonneau with Twillfast fixed with aerosol adhesive (sourced at Maplins).
This is how it looks - (those white specks of dust are annoying......)

And I extended the fasteners to make sure it won't 'pop off' on the road.
Here's one relaxing on the hood cover:

This is how it looks fitted (offside). The loop under the hood frame puts the load sideways to the fasteners making it less likely to pop off, and the low location allows the hood cover to fit easily over the top. This is an improvement over the original solution.

I've taken the other piece of Twillfast to the trimmer today to have it stitched-edged. Hopefully he'll get it done for next Saturday. Fingers Crossed..........