You do not have to remove any Tupperware to do the shifter adjustment.
It can be done, but is FAR EASIER to take off the silver peg mounting plate. If I recall correctly it is 3 or 4 screws, and just take it off. No big deal.
Then IF you have a Torx socket of the proper size you remove the screw, move the shifter one spline down, reverse the operation and you are done. Might take 15 minutes if you stop for a beer.
There have been several more detailed posts on this. the search function may reveal them but it really is a simple job. My suggestion is to put the bike on the centerstand and carefully measure the distance of the shifter to the garage floor. Write it down. Then do the move one spline at a time. Some guys have marked the shifter and shaft with a marker to keep up with things. A good idea especially if you don't do the ruler thing.
I had to move mine to adjust for new boots. Others have mentioned this as well. A little move is quite effective.
Just for the record- I have also done the turnbuckle thing but it is hard to do- upside down laying on the floor in a very cramped location, and even after getting it moved it may not be enough to solve the problem.
Really, the peg plate is a 15 minute job.