A code reader is a waste of money when attempting what YOU are trying to do. If you are serious about what you plan to do, you need serious tools. Now, I do not know all the answers, but I know the guys who do, they are my "brain trust".
"Pizza's Brain Trust" says:
I think his best bet is to buy the computer setup that The MSS is selling.
Here is their announcement:
@GannyX on this forum is James - you can contact him here via PM or at:
https://themercedesswapshop.com/