Teheuti
While I basically agree with you, the fact is that The original Golden Dawn members read using the Golden Dawn OOTK method with European decks - TdM, Italian, Swiss - whatever they could get their hands on. [Added: I just saw that Lee said essentially the same thing.]Except there are no decans, zodiac signs or anything else in the TdM because it's pre-Golden Dawn.
Why not just read what's actually on the TdM cards if you want to use a TdM?
If you want to read with the Golden Dawn system I think you're best using a deck that is based on that system - Thoth, RWS or their derivative decks.
However, in a discussion on reading the TdM I believe most people are looking for a more direct interaction with the cards of that deck.
If you want a pre-Golden Dawn TdM reading system, then you really need to go back to Etteilla. Even though he created his own deck, he also influenced how people read the TdM. For French contemporaries of the GD, look to Oswald Wirth and Papus. Probably the chief mid-20th century influence is Paul Marteau, who unfortunately has not been translated into English. He combined suit+number symbolism with pictorial elements found on the Grimaud TdM pips.