I have quilted two almost-king sized quilts on my vintage Bernina 830 Record. I have a sewing table for my Bernina, but it's not very big. I actually found using two 24"X48" tables worked the better than an extra banquet table. One behind my sewing table and one to the side, turned perpendicular. I only needed the table to the side when I was working with the most to the left side of the needle, typically in the middle sections of the quilt. The table behind my sewing table helped the most. Doing whatever you can to reduce drag on the quilt helps tremendously. Wrapping the table with clear vinyl worked for me. I also waxed my sewing table with Johnson's paste wax. My machine has a slick metal surface, but a plastic one might need something else such as a mylar mat.
I found that the easiest quilting design was a wavy line with my walking foot, because it took minimal turning of the quilt. Using quilting gloves helps tremendously with gripping and making the wavy lines. Free motion quilting on a large quilt is not something I would try with the limitations of my sewing machine size.
Bobbin access is important. I have a vintage Singer 15-91 that I actually bought just for machine quilting, but the bobbin access is from the machine bed. This requires removing the quilt to access the bobbin case each time a new bobbin is needed. I can reach my Bernina bobbin underneath the table surface fairly easily without having to remove the quilt. The presser foot lifter is another feature I only use when I'm quilting, it helps every time I need to reposition the quilt.
I also learned to only quilt in short sessions. Handling a large quilt was very hard on my back, shoulders, and neck.