With such a beautiful quilt, you will do it just fine. Just take your time.

I do this with the ditch foot with my Janome 9400...it's tedious; take many breaks....good lighting is essential....don't let the machine get ahead of where you're comfortable.......and yes, much turning of the quilt......the largest I've done is a queen size....

I do FMQ stitch in the ditch with my DSM. I have just made myself learn to do it because I don't want to turn the quilt. I don't use a ruler because I have not really used mine enough to be comfortable with them. I use a closely matching thread color. The last one I did was my log cabin QOV and I did each "log." Your design is more intricate, of course, but you can do it. You will be an expert at it when you are done.

I have one of the "ditch" feet you mentioned, but I really almost never use it. When I need to SITD, I use a walking foot and just take my time.

Watson, can I suggest that instead of ditching everything, that you sew about 1/4" inside the seam? You'll get the same impact from quilting, but not have to worry about sliding out of the ditch at seam intersections, etc.

Hope you can follow this.
(If you don't want to give it to a LA and frankly not all will do ruler work.) After you have 'basted' WELL, pins or stitching, plan on starting near the center. Work in a continuous path outward only partially completing a section or block, turning no more that 90+ degrees off your starting position in either direction. When you get to the edge, go back to the centre starting point and again work out in the opposite direction. Continue this pattern on either side of the stitched area carefully linking with the already stitched edge. Yes you may have to overstitch a few places/times but this way you will never have to turn your quilt 270 or 360.

Thanks, everyone for your help and suggestions.
I have been practicing with leftover blocks and I think the FMQ will be OK.
I bought some Decobob thread in Lilac and Charcoal, which is an 80 weight and it blends really well as long as I'm careful. Took some adjusting, as I double batted it, but I think I've got it right.
Now I just have to get up the nerve to start on the actual quilt!


Watson

Good luck, Watson. I can't wait to see it finished. It's positively gorgeous.

When I SITD/FMQ I use YLI invisible monofilament thread. Don't have to worry about matching thread color :-)

The stitch in a ditch foot does make it easier, because it has the metal piece in the middle to help it stay in the seam, I have a Viking and can use mine with the walking foot, it has interchangeable with different feet