How about a local (or national) scheme where we can go and deliberately submerge in full wading kit etc (after coaching) and safely attempt exiting the water under controlled conditions (boats/divers) ?
Having done my offshore survival course recently (25 years on from my first one) the "dunker" might put anglers off ever going wading again. Deliberately going for a swim in full waders with a life jacket in cold water will scare the be-jesus out of most people.
I had a dunk in the Dee a few years back from a canoe and I can tell you it isn't pleasant. The cold sucks the breath from you and you become very disorientated, very quickly. Putting someone through that will more than likely just put them off fishing for good.
It would also be VERY expensive and a hard thing to organise. However, if angling clubs had talks by those in the know on the subject, like the Coastguard, then that might be a better attended event, in a friendlier more relaxed atmosphere.
Despite the fact that we spend a lot of time on and in the water most of use don't realise the danger it poses. Might be time we did something about that. Life jackets are cheap, lives aren't.