The dust seal comes right down easily with a tiny flathead screwdriver. It's hard enough to saw your thin cleaning tool up and down and around getting all oily without leaving the dust seal in place.
I cannot answer the coke bottle question, thou recall some writing they chopped up a plastic bottle of some sort to make such tool.
First time, I did not remove my rock guards, later I did and it made the job easier... and I did a much better job. I see no reason to pull the fender thou.
To me it seems easier to just remove the fender than the rock guards

Once you figure out the right (small) tools, the guards are easy; one nut a 1/4" stubby ratchet/socket, the other a ratcheting box wrench, high and low. But be careful, the small nut will slip down inside the fender/fork mount and it takes a magnet to retrieve it. Like the interstate bulbs, you have to do the job by feel.