You could do it, and if it makes you happy, be all means, do it. I'd show up on early side (might get in a few minutes early), tell the waitperson that you're looking to move it along. But it could be tight, and you still have to catch a monorail (or less reliable, a boat), get through bag check, into MK, and find your spot (among a crowd).
You may already know, but Wishes is really quite good from either the marina or dock at the Grand Floridian. That might be a great alternative.