Every time I see someone say, "It's just stitch in the ditch," I think, "There's no "just" about it - stitching in the ditch is HARD!!!!"
I'd rather take a beating than try to stitch in the ditch - I only do it when I absolutely have to. With all that quilt pulling and tugging against you, your stitching wanders around all over in the vicinity of the ditch. Keeping it straight is insanity.
Yes, you'll feel like you're wrestling a grizzly for a while. And dealing with a large quilt on a domestic machine might never become a walk in the park, exactly, but it does get easier. Instead of trying to sew straight lines, use a serpentine or rippling stitch to wander back and forth across the seam - that's what it wants to do anyway, so make it look intentional. ;)
The only time you can't get away with that is when you really need that straight line - to stabilize borders before FMQ, for instance. Then, you just have to bite the bullet and sweat it out.
Good luck - I feel for you!