I would advise against stitch-in-the-ditch. Very nerve-wracking and slow to do. Straight or wavy lines are fast and easy to do with a walking foot. The nice thing about wavy lines is that they do not need to be evenly spaced apart, making them faster and easier than even just straight lines that are not in the ditch. I will try to attach a couple of examples:
http://www.bijoulovelydesigns.com/20...-tutorial.html
https://www.youtube.com/watch?v=CvBjmFimpgA

Also, I highly recommend heavily starching the backing fabric and the top before you sandwich. This stabilizes the fabrics so they are much less likely to shift or stretch while you are working, minimizing the possibility of tucks or puckers.

Edit: I agree with accordion-pleating the quilt that is under the arm of the machine. This worked much better for me than rolling. A roll can get somewhat stiff and unwieldy; the loose accordion pleats are easier to adjust as you work.

I do like the idea of the swerving lines.

The quilts you girls showed in the pics above are so pretty, and nice quilting.

Oops. I see you've already tacked the sandwich together. In that case, you can apply several layers of spray starch to top and backing to help stabilize fabrics. A fan speeds drying between layers of spray starch.

Susan- I've always been a hand quilter but am learning FMQ. I am doing a twin size for my brother and it's not too bad at all! I've been dreading it but Ginger's Mom told me to go for it so I am :)
I have a Juki and the harp is about 9 inches. I never thought I could do it but I am!!!!!!!!
So I know you can too. Trust me, I'm very very new at this!
Oh- the puddle method works for me. Also Machingers gloves.

Forgot to mention- I'm doing something like a large stipple. It won't be the prettiest but my brother won't care. He doesn't know anything about quilts except that his little sister is obsessed with them!!

I only roll for Stitch in the Ditch. Anything else I either fold or puddle/push. Check out Ann Peterson's class at Craftsy about quilting large projects on a domestic machine. Lots of good tips.

It can be done, I puddle and jam my quilts, I have quilted a queen size on my Bernia 1008, with a 6 inch throat. It can be done. Oh, this was free motion.

I will let all of you know how it turns out.

Susan, I quilted many large lap quilts to twin size on my Brother SQ9185. It has the regular size harp. I didn't roll the quilt through, I kinda shoved and spread it out as I went along. It was sort of hard in the beginning when starting in the middle of the quilt but got easier when getting to the sides. It is doable. But after about 2 years of doing this I decided to get a Juki with a 9" harp. So much easier on the shoulders and neck. Both SusieQOH and I got out Juki's at the same time and both are starting FMQ for the first time. Good luck and just remember to have fun and enjoy it. It can be done.

If you're planning to FMQ the top, you can turn your machine so that you're actually sewing with the small end of the machine facing you (large/motor end far away from you, towards the top...). This gives you much more side to side room. This works because the hopping/FMQ foot only touches down when making the stitch and the feed dogs are not engaged/stitch length is set to zero.