The climbing courgette is Black Forest IIRC, don't worry too much about weight on trellis grown squash/.... I had a Bon-Bon last year that set two on the ground and two on the border fence of the plot.... the two hanging ones were about 4 pound each, so although not huge, about the size of any decent eating squash, on the ground there were few if any tendrils on the plant, around those fruit there were loads... the plant knows what it is doing......
chrisc