bob, I've tried progressives, couldn't stand 'em. The ones I was sold weren't rectilinear, i.e., they rendered circles as ovals. I sent 'em back, got trifocals. Still wear trifocals.
I now use a loupe for focusing, +4 reading glasses for looking at composition on the GG.
Since I shoot with 2x3 Graphics, I've cut a piece of nominal 4" thin-walled PVC sewer pipe whose belled end just slips over the camera's focusing hood. I've lined the pipe with flocking paper from Edmund Optics. With larger formats, I suppose its a dark cloth or nothing. I've never tried a BTZS tube, have you?
You might also want to look into getting a ratty old used Hassy chimney finder for focusing and looking at more of the image than most loupes will show. Also useful for looking at transparencies on a light table.
Cheers,
Dan