It looks possible to do the Gravy Pud during Tanky's.

All you need to do is run over from Marsden (9am start) to Crowden, pop down to Tintwistle (about 2.5 miles down the valley), do the Pud (11am start) and then rejoin Tanky's route at Torside or at the Snake Inn.

It adds no more than 10 miles and 1100ft, and the timings look about right for the faster runners to get over to the Snake Inn before the 1:30/45 cut-off. Anyone fancy giving it a go? Think of it as a race within a race - Tanky's Gravy Pud Trog.