This is the technique the Roman senate actually used, and it’s exactly your Memory Palace turned toward a new job: instead of storing objects, you store talking points, one main idea per loci.
Outline your speech first, into clear sub-topics, not full sentences, just the core idea of each section. Then walk your palace and drop one sub-topic image per stop, in the order you’ll actually speak. When you’re up in front of people, you don’t recite from memory word-for-word, you walk the palace in your head and let each stop remind you what comes next, then speak naturally from there.
This is also why a dedicated “speech palace”, separate from your everyday-errands palace, matters: you don’t want your grocery list showing up mid-presentation. Build or reuse a palace just for this purpose.