Yesterday I was at the Bernina dealer, and saw the 1/4 inch foot with the "fence" on it to sew at 1/4 inch. I didn't know that was available. I'm wondering if I could move my needle one step to the right to sew a scant 1/4 inch. Next time I go there, I will look into that more.
I also have the fabric fence that screws onto my old Singer that works well.
And I bought one of those magnet things. It won't work for scant 1/4 inch on my Bernina, because the feed dogs are in the way. Perhaps I could move the needle.
On my Singer, the magnet hangs on tight, but if I bump it hard accidentally, it moves.