Hi Guys,
thanks for all your replies, I had sweeper today, so I knew I would be a little nervous. I applied anti-perspirant stick to my entire thumb ( I wear a wrist device) so no need to chalk up the palm anymore, 45 minutes before I bowled. Didn't help much, maybe less sweaty than normal. Tried the grip bag, and finally settled on really using the puff ball a lot. Using the puff ball I was able to keep my thumb dry enough. I just powder up in the back before the shot. If it's really bad, I'll tap the thumbhole before I bowl.
I have a tournament next week, If I can get one, I'll try the portable fan next, hopefully I'll use the puff ball less as it does leave quite a pile in the back. Couldn't respond sooner since it's not a problem with practice.