I have spent lots of time on the big pond. I have seen glass calm and I have seen 6+ footers that made my a$$hole pucker. More importantly, I have seen the conditions change extremely fast from one to the other. Depending on how fast your boat is, I wouldn't be more than 30 minutes from shore in a pontoon. And of course, portable, floating VHF radio and some type of GPS.
That being said, on a calm day, she should be no problem. I have skippered a solid top pontoon in 25-30 mph winds and solid 2 foot white caps on large inland lakes. It wasn't fun, but it worked. I wouldn't want to push it any further than those conditions.