Possibly abolish the deputy leader role?
I look at all this and here Macmillan whispering 'Events, dear boy, events' about what is most likely to blow government's off cpurse. (Note i know there is some question about if he said it).
To be fair a lot of the current govt's issues are around self inflicted events but that is a feature of govt too. Indeed with Rayner it is her insistence on previous resignations for Tories that makes this likely to happen, and the Tories of course responded in kind because that is our politics now.
https://www.bbc.co.uk/news/articles/cgmzg1gl2p3o