When I baste large quilts I prefer to stand rather than kneel on the floor. For all quilts that are as long or longer than my dining room table I use it for basting. Here is a quick overview of the procedure followed by some pics. Please comment with any questions and I can clarify.
1. Place backing wrong side up with the middle if the backing in the middle of the table.Leave excess hanging as equally as possible to all sides so you you can baste the center out and use the weight of the quilt to help keep things nice and taut.
2. Spread with your hands to even out wrinkles. Then use big office binding clips to hold the backing tight all the way around. I use 2" clips and they're maxed out on my table. You may want to measure before you buy your clips.
3. Spread out batting. Ensure that this is also centered on the table and square with the backing. Use your hands or a large ruler to smooth out any wrinkles.
4. Find a husband or child of appropriate age and height to help lay out quilt top right side up on top of the batting. Center this in the quilt batting/ backing and spread out wrinkles with hands or acrylic ruler.
5. Use more binder clips and clip between the ones holding the backing in place to secure the entire sandwich. Be sure that everything is remaining square as you clip. (I use sashing and borders to eyeball if it is nice and straight).
6. Pin baste all the layers as normal leaving a fists width between pins.
7. When this center section in completely pinned you need to unclip all the office clips and move to another section of the quilt.
8. For the next section you will use the binding clips first on the side if the quilt that is already basted. Next pull up the top and batting and pull taut the backing to secure it taut.
9. Repeat steps 5 and 6 above to baste this area and the move to another end of the quilt to re-clip and secure again.
Depending upon the size of table and quilt you may need to baste in several sections. For my large dining room table the most I have needed is 5 sections. The middle and 4 sides. But this was only necessary for queen sized and up.
Try it out and see if you like it. If you don't have large dining table then a large folding table or even a small card table would work as long as it has a hard top and not a padded top.
I can answer any questions you may have. Just ask in the comments or shoot me an email. Enjoy!