You really think a plug and play unit is more hassle than disassembling your whole dash? The reading and watching I’ve done suggests installing one of these units is anything but a “big hassle”.
What sort of tablet are you looking at to fit in the iDrive cubby? The iDrive display is super wide and short, I can’t think of a tablet that would fit in there that wouldn’t look silly. Have you got a link to what you’re thinking?
In any event, it sounds like you’ve made up your mind so not really sure what you’re looking to get out of this thread.