Hi

I have been using just an L shaped piece of steel that screws to the existing rear flap. Works fine in long grass on Victas ,Rovers and Sanlis. The piece of steel keeps the flap up and is held against the mower by the spring. Takes about 5 min to make.

Been doing this for years
Not as good as a Utility. Mower is a bit heavier and it does clog a little in very long grass but it's easy to unclog by tilting the mower backwards so the flap lifts up a bit. Leaves a big clump of clippings though.

Jeff