thepolyparrot

You don't really have to cover the feed dogs - just set the stitch length to neutral or "0" to keep them from moving forward or backward.

Yes, reduce or eliminate the pressure on the presser bar.

There is a vintage quilting foot made for the back-clamping machines - it's not like a modern hopping foot. It's just a very short-toed foot that has a removable & adjustable guide you can attach to it. If you can find one of these quilting feet, that will probably be your best bet.

In the meantime, you can use whatever foot you have on hand to play around with the idea. Make 14-16" squares of muslin with batting in between and start stitching. Your visibility isn't going to be great, but practice looking ahead of the foot - keep an imaginary line going where you want it to be.