There have been a few attempts at building new sets of “consistent mnemonics” - this thread talks about @sporadic’s attempt, and @Rowena also drops in to discuss her approach (which reminds me a bit of fingerspelling in the sign language context). You might find it an interesting read.
As sporadic notes, there are around 900 unique readings of two morae or less, so this is a pretty big job. You may want to limit this only to readings where, as you mention, there is an ambiguity between the English mnemonic cue and the reading. So perhaps keep 末 as suing Stephen Hawking when you get all the way to the end of the universe and find out it doesn’t actually go on forever as advertised, but replace 数 with すzie Quattro wearing うgg boots while counting a pile of records.