bkay

I looked at the pattern. It's a nice design. The question is, how big is your basic block? By basic block, I mean one white rectangle sewn to one colored rectangle. That will tell you whether your plan will work. Your batting says you need to sew every 5 to 6 inches. If the remaining unquilted space exceeds 6", your plan won't work.

If I were doing this, I'd save that batting for another purpose and get one that gives you more unquilted space, although 8 inches is about the maximum.

Another option is to tie the quilt. Jordan fabric has a video on how to tie a quilt.

No, I would not leave the border unquilted. If I were doing stitch in the ditch, I'd just keep going on in that straight line right off the edge of the quilt.

bkay

Another thought, as you you just want to get it done, is to stitch in the ditch and then go back half way and stitch on top of the block. so all of your quilting would be on the diagonal. I often use clear thread. (I've found that Gutermann color 111 (no color) works best on my machines, which are vintage Singers. It's available at JoAnn's, which is not too far away.) I use a regular thread in the bobbin. To keep your stitches straight, you can use strips of masking tape and sew along side them, not on the tape, as it is really hard to remove if you sew over it.

I hope that makes sense. If not, let me know, and I'll try to explain it better.