Spengler is on a list of political theorists and philosophers whose opinions I think would be super interesting to see relative to this world, but whose raw theorising and opinions I both don't feel that I can organically fit in, nor do I see myself as capable of taking their life's work of theory and developing it further in a fictional world.
I see him as being more positive towards Lettow-Vorbeck than to Hindenburg, but also finding the man to be, ideologically, another flavour of the same old-fashioned and archaic Prussian who created the Great War. I am no expert in his philosophy, but as far as I understand it, he was more the proponent of someone like Stresemann or another temperate nationalist with socialist tendencies.