Well, it looks like a solution has been found, I had a spare old electric fence battery in the shed, so I dug it out, put it on the battery charger in recondition mode for 36 hours, and did a test inflation. It worked fine, which is handy considering the battery must be 10 years old.
I suspect however that Rich's solution of blowing the thing up first and portering it to the launch site might end up being the preferred solution, but it's nice to have the option.
