One point on the spade tyr ground anchors, they all have flat spades. Has anyone tried welding a strip of metal perpendicular to the balde at the back. If you thinking WFT bear with me
One of the modules last year involved ground anchors, which in true harper style was about half an hour of theory followe by an hour and a half of constructive playing. The main piece of quipment we were using was an old trqactor PTO winch with a built in ground anchor.

Not the best of pictures but you get the idea.
The anchor was a relativerly a flat blade, so similar in concept to the spade type ground anchors used on comps. A fter a few measured pulls a perpendiculare plate was bolted on to the top side. The result was it blocked soil from freely flow over the blade and the blade didn't go as far down in to the ground, but more importantly was the force required to drag the ground anchor through the ground was greater despite the shallower depth. Has this modification been tried by off roaders? if so what were the results?
Stevie D, how quickly are you trying to extract your self? The spade anchors appear to be the quickest for competitions, but where speed isn't so critical then there are several other types wich should be more effective in soft ground. As well as the pins through a tube/plate mentione above there are also screw type anchors which should get far more purchase in very soft ground, but obviously arn't much use on hard ground and take a relativerly long time to set up.