I would go with The Planner and double the frequency of the existing Euston - Crewe to every 30 minutes, hopefully timed with a reasonable connection at Rugeley TV with the Chase Line trains.
An alternative I have thought of is now that the power station at Rugeley has been demolished, and depending upon the underlying ground conditions (as there used to be heavy coal mining activity near that area), is whether grade separation for southbound trains may be worthwhile?
According to the London North Western (North) Sectional Appendix (Page 7, 02/04/2016), although it may be easy to continue from Rugeley TV northbound to Stafford, southbound towards the Chase Line the train would have to weave across 4 tracks to reach Platforms 1 and 2, and have to be timetabled to make sure there are no other northbound or southbound trains between Colwick Jct and at least Rugeley TV, and nothing timetabled northbound to be in Platform 1 too (hope I got this right).