I just spend 12 days in Central America, did four dives plus another bunch of snorkeling, kayaking and other on-land videos. Had to open the housing maybe 4-5 times to change batteries during the whole trip (only did it indoors, while on A/C).
From the 10 anti-fog inserts that came in the package, used only 6 of them - I was being on the cautious side, I could maybe just have used only 2 pairs and still be ok.
I feel that microwaving them would just melt and fuse the silica, I just grabbed some that I used and microwaved for about 1 minute. They feel drier but I'm not sure if the water is all gone.
if you are staying much longer time and feel like will need them re-activated, I would suggest bringing a piece of aluminum foil so you can make a little "tray" and ask a restaurant to do it for you.
