Just play, if we waited for no rain out here on the wet coast we would never play. Years of rain from drizzle to heavy stuff has had very little effect on any of my AEG's, pistols and gear.
When you get home take your guns out of the cases make sure the surface is dry and LEAVE them out of the case for a couple of days. Before they go back make sure your case foam or case if it is a soft case is good and dry.
Googles will get wet, so carry a cloth or old piece of towel to wipe them while you are in the field, fogging is no worse than any other warm humid day.
Oh bring dry clothes and shoes for post game.