Serendipitously, on a recent long trip to a very wet climate, I forgot my trusty, but annoyingly fragile Dri Duck pants. We knew we were in for quite a bit of rain, plus some cold-ish weather (even in summer, yes it was summer where we were), so I ducked into a local gear store and for about $35 walked out with a "mac in a sac rain trouser".
Very light! 4.8 oz for the large, 0.3 oz heavier than a dri-duck pant, but seems much more durable.
Here's a link to an Amazon version, looks the same, unfortunately only in XXL on Amazon, but surely it can be found elsewhere:
https://www.amazon.com/Mac-Sac-Water...186735&sr=8-16
I've been searching for a sub 5 oz waterproof pant for a while, finally found it. By the way, the fit was pretty small; I normally wear a medium pant, those seemed snug, so I bought a large, which fit well, though generous. I'm a 32" waist, 33 inch inseam. The mediums were a bit short, plus snug over other pants.
I tested these by walking under a 1900 foot high waterfall.... see pic... completely immersed, my legs stayed dry.
Just passing on a find.
(PS: I'm not meaning to debate carrying rain pants, that would be for the UL forum; I carry rain pants mostly for warmth and the occasional downpour)