If the cham drinks the cham drinks. Thats all that matters. Some want the whole caged hosed down, and hides during the rain and come out when its over. Others like to take a shower and wont drink unless they are getting rained on. If your cham is on of the smart ones that "knows where the water is" you can have just that area. Each cham is different. Mine requires 1/4 of the cage to have a sprayer, some times when it goes off he will walk under it and get a drink, other times when it goes off he will walk out of the area because he doesnt want to get wet.
Since you are into diy, you could take one of the 2 nozzles, and place it in a jar with a pinhole at the bottom to make a dripper. So it would "rain" for 1-5 minutes, and then "drip" for 10-15min afterwards.