ground anchors for gripples

[PG]

Has anyone found a good way of getting a secure fitting into the ground for white course path junctions where there's nothing around to attach a Gripple?

I have found these. I phoned and they suggested going for 30x540 as they are more secure in softer ground than the cheapest ones. They recommend using a heavy hammer (e.g club hammer) to get them in past stones etc, but they unscrew with a big screwdriver or adjustable spanner.

Anybody tried these or any other solution?

[Strider]

We use modified dog screws, where a bolt allowing you to use a car wheel spanner has been welded onto the top to enable you to screw them into and out of the ground. However, we're lucky that we have a man in the club who is handy with a welding torch to allow these modifications to take place

[Gnitworp]

I've threaded my wire under bundled-up, double-rooted bramble shoots, which of course might not be available where you want your controls.