You are being overprotective. I raise my chicks outdoors in an uncovered run with our typical PNW spring rains and it has been no problem. I do have excellent drainage and I pile lots of deep litter under the brooder so rain/mud isn't an issue for me, and there's a variety of clutter in my run (as well as the brooder itself) for the chicks to take cover under if it rains.The rain is the big factor for meor I am just being too overprotective .
Your bigger issue could possibly be needing to do see but not touch with limited(?) space if you don't have enough available rain shelters for the adults and babies to use separately.