Just to throw a spanner in your works
Last year was my 17th Fellsman. I have always previously taken the southern route across Fleet Moss even before they decided to move the Middle Tongue CP for the first time last year.
But last year I decided to go down the road a re-ascend from Deepdale, and I can say that this was MUCH faster, as long as your are prepared to jog the tarmac section - I'm talking about 10 minute/miles. The re-ascent is only a little over 1000 ft and not 1500 ft as previously mentioned so is not that far, and it's over pretty good ground.
You've already done 38 miles when you reach Fleet Moss CP, and it depends how strong you are feeling as to whether you can continue to run across the rough moorland. I think the proof was that I did my fastest ever Fellsman last year.
DB