What can I do to get my spouse to appreciate me as a stay-at-home mum?

I do not think there is anything more that you can or should do to make him appreciate you being a SAHM. If he cannot already remember all the time and appreciate what you do, then why put more efforts. Majority of men have bad memory, a default 'take for granted attitude' so leave it at that. Sometimes, as someone here shared that making him read an article about SAHM would remind them how much and how well you manage things. And that evening may be a dinner date or an appreciative evening for you. ;)