I think i'll buy the "toblerone" and hope for the best, It's only £30 so it's not like i'll lose much if it's not suitable and as you say can always trade in for a terra nova should the need take me.
I'm hoping to do (instead of LEJOG as previously planned) an east to west to east type ride in august. Not going to hammer it out at 180 miles a day, just plod along and camp so hopefully it'll cope - I can do this trip for the cost of train fare for LEJOG so that would be ideal IMO plus 200 miles less which is a good tester for myself and gives scope for increase