Could they stop in the southbound direction bearing in mind most of the trains have 12 minute stop at Wolverhampton without affecting other services?
(I realise the calling pattern would unbalanced northbound and southbound).
The 12 minute stop is deliberate to allow performance recovery before entering the West Midlands (it is, strictly speaking, required in the Timetable Planning Rules in order to allow a 20-25 minute turnround time of the train once it gets to Euston as per a standard West Midlands service, rather than the 40 minutes normally required from Scotland)
Plus, I beleive it is followed closely behind from Stafford by the Manchester-Bournemouth XC service, so doubt it could run sufficiently later south of Stafford to permit a stop (unless Norton Bridge flyover permits the XC to be accelerated to be placed in front instead)