agree.
+1 to your maamid demamid eitzah with a zip tie. (Though it is a drop of a chidush, I can't see why it is different than the standard mamaid demamid of the support beams underneath...)
If you zip tie the schac mats directly onto the support beams, then the zip tie might be called a direct maamid to the mats (albeit the holding down variety of maamid as opposed to the normal holding up variety). By putting a bamboo pole on top of the mat and zip tying around that as well, the zip tie becomes the maamid of the bamboo poles, which is the maamid of your mat (the actual schach of the sukkah).