I use the 505 and it doesn't take but a quick swipe for a single block.
You said to guess the next step, the method I'm using has me baste 1/2 inch around the block with washable thread on the top. It does keep things square and so far I like it.
I've looked at the current method you're using and I don't know how it would work with setting triangles. I'm planning to sew my on point blocks in a strip before I quilt. Also I'm wondering now you accommodate a wider sashing. Lots of questions....
BTW...I was raised in Washington state about 2 miles south of British Colombia. Lake Osoyoos was shared by both countries. Then it was so simple to cross the border and shop. Now it takes a passport!