David,
A general note on raingear--it is not to keep you dry; it is to keep you warm so that you don't develop hypothermia. Heavy rain gear will protect you from the rain, but the sweat inside can get you just as wet. This is especially important on a summer Camino where getting hypothermia is less likely (but not impossible) but sweating inside rain gear is very possible.
That being said, my wife loves her Sea to Summit UltraSil Nano Poncho (about 5oz; not the heavier one that is also a tarp). She is a hobbit and the poncho covers most of her. She had one of those breathable poncho from Eurpoe (Ferrino, I believe), but gave it up as too heavy. The poncho design, which allows air to circulate under it, makes the "breathable" (until it wets out--about 45 minutes) unnecessary.
I've always carried a rain jacket instead because I also use it as my only warm layer on a summer Camino (ponchos, precisely because they get more air circulating, and are not as warm). Currently, the best I've found is the Columbia Caldorado jacket. Better because it uses OutDry, which will not wet out (and therefore lose its breathability). And it has decent vents down the side, although often I just end up leaving the front zipper open to vent (again, I'm not worried about the drops of rain that get on the front of my shirt--when I'm walking I'm generating so much heat that it will dry).
For a summer Camino I agree with the suggestion to not bring rain pants--they would be too hot. Instead, I'd bring a rain kilt. Lighter to carry (2-3 oz), and much cooler. Look at the small cottage manufacturers, especially ULA, Zpacks, Antigravity Gear, Helium Gear, Mountain Laurel Designs and Enlightend Equipment.
Buen Camino,
Jo Jo