If the training continues unaffected by injury then I see 5th being feasable.
An extra 5 laps over last year? 25% further? Unless you were really not 'on the ball' last year that's a massive ask!
What you fail to see is last year's pdf – one of us fell asleep for 4hrs after puking for Britain at 3am when laps should have been ridden.
It'll damn near kill me / us, but we're both of the same mind set & I think we can improve a little over last year, not get sick & so I think clinching 5th would, with a combined age of over 100, be a real achievement.
29HT for me, although I'll have the 4 inch Turner Flux with me if I feel the body is getting a little tired / battered.