It is a tempting proposition, but 10km is a long distance to travel with 6kg of aluminium strapped to your legs[1]. Then there's the matter of it being in early June at the height of exam season and in London too. Whilst I can personally make it other people, especially those north of the Midlands, are going to find it hard making a case to go.
If we do go, I vote someone bring a rental van: after doing about 5 or 6km and getting completely shattered we can dump our stilts in the van then continue on foot as usual, and if we recover we can mount-up to cross the finish line in style.
I've read that other people have done the Walk for Live entirely on stilts, but then not everyone has the same muscle mass as those superhumans :p
[1]My A2-level physics tell me that will take:
Downward force of stilts: 6kg * 9.8ms^-1 = 58.8N
Extra energy required: 58.8N * 10,000 = 588,000J.
So you need half a million extra joules of energy to complete the Walk for Life with stilts (as opposed to doing it normally). For comparison, a Twix bar has about 580J. So you'll need to consume about a thousand twix bars to get the energy to do this.
...I think my physics are wrong somewhere. Anyone feel like correcting me?