Maybe using a Sharpie on top to mark what corresponds to 1/8" from the needle, then using that line as a guide to the applique' edge? You'd basically have to make your own circle on the clear foot (and mark on TOP of the foot so the ink doesn't transfer to the quilt top. You have to train your eyes to follow that line and the applique edge, NOT where the needle is.
Short of that, if you've got someone who could modify a second clear foot (toe) to be that 1/8" (grind it down) all around, kind of like a mini clear foot, then again, train yourself to watch the edge of the foot relative to the edge of the applique'.
I know it's hard - we want to watch the needle. But with echoing, you need to watch the foot and the thing you're echoing instead of watching the needle.
Great ideas! I will experiment with marking my clear foot (with a water soluable pen until I get it right!). I love your idea of a mini-clear foot that had specific distances you could choose from. Wouldn't that be a really useful foot!