I think your idea of a notebook of sketches is a very good one.
Recommend you read this thread https://forum.artofmemory.com/t/miniature-memory-palaces-including-your-palm/28864
There’s a rich discussion about different ways to implement memory palaces including some sketches, (and of mine).
There’s no reason it all has to be hand drawn. One could print out a picture of a suitable space and then draw on that. And one can make collages too. There’s no end of clip art and so on that can be just pasted into a simple program or printed, cut out and pasted on.