I also was wondering how large can you go with the YUPO paper without it buckling or having ripples when framed and matted?? Is there anyway to prevent this from happening??

This is difficult for us to answer as there is no rule of thumb. We have seen large artworks done on YUPO mounted without any ripples, but we don't know if the YUPO was mounted with hinges, archival tape or dry mounted. But it's important to note that even very large works of art done on regular paper will often show rippling (if it's mounted with hinges for example) as the paper expands and contracts over time due to the environment.

Also find below two truly informative articles written by Chris A Paschke, CPF GCF of Designs Ink that appeared in 'Picture Framing Magazine'

“Yupo Part 1: What To Do with Yupo”
http://designsinkart.com/library/M-YupoP1-201511.htm

“Yupo Part 2: Mounting Synthetic Papers”
http://designsinkart.com/library/M-YupoP2-201601.htm