More thanks to Doug for an excellent write-up, still very valuable 12-13 years later.
Had all very similar experience of the diesel fog/trail. In my case it wasn't the hose leaking (my original supposition) but the front nut had just undone itself and pipe fell out! Equals vast quantities of fuel over the road. (The support bracket on the pipe had fractured; obviously some time ago).
Tried with breakdown guy to get nut re-engaged, but without success due to such limited access, so knowing we weren't going to be be able to tighten even if we got it on, she came home on a recovery truck.
The real game changer was the advice that I only had to remove the battery/box rather than the radiators etc. That plus the knowledge that it was a practical possibility to make/modify a spanner that would do the job.