Night sleeping. - Great with A/C... If you were in a tent, not too bad at night. A bit chilly in the morning & everything is soaked with dew.
Other things we do:
Panchos - Buy before you go. Rain isn't too bad, but you'll freeze when you go inside
Water bottles - to refill in fountains. Buy the crystal light flavor packets.
Electric water spray bottles - again, buy before or pay outrageous rate in park
Spend lunch @ camp - Hot part of day, swim & recharge.
Teva's or sandles - Walking in wet tennis shoes is draining.
Rains can last 10 minutes to several hours.
We were at Hollywood Studios yesterday. 70% chance of rain. They cut a couple of shows, but we had a great time and saw most everyhthing.
Also, hint: If you are hitting opening, send the fastest person to the most popular ride to pick up fastpasses. Remaining group head to 2nd most popular ride, fast person can generally make it. That way, you hit the two most popular rides early. We did this yesterday with Toy Story & Rockin Roller coaster. Both done by 9:40. Up to 2 hour wait later.