Last summer in New Zealand we watched this video: http://vimeo.com/54896465. At minute 3.30 there is an accident where somebody hurts their back pretty bad. While we were watching, we were cringing at their extraction method and asking the question "is there a better way"? I think that the best resource that we have for packaging someone with spinal issues for transport is a (their) kayak. It can be dragged, lifted, modified and destroyed.
If I found myself in a situation where I though that my back was broken, I would want my friends to look after me and do what ever they had to make sure the situation didn't get any worse. If this means chopping up my kayak, then I would say go for it.
During some downtime this week in Canada, we tried out what system we would use (on a kayak that was broken and retired).
First we chopped out the cockpit to make a hole big enough to slide a person into. We did this using our river saws.
The next step was cutting some holes in the bottom to thread our slings through the kayak. We made the holes with a small pen blow torch and a knife.
The slings are used to keep the patient in place.
Slings are used to make a full body harness
The end loops of the kayak can be used to make an attachment point for hauling. I would use a separate safety line that goes directly to the victim as a back up.
Rata was secure in the stretcher and didn't move at all.
Handles could easily be added to the sides to allow for easy carrying. You can use the center pillar to make a neck collar and head support.
Once we were done, Lief had a chainsaw which made it very easy to finish cutting up the kayak to recycle it.
Rata enjoying it a bit too much. Safety first.