Joe welcome to the forum! Couple of issues at play here. Gray water in and of itself is not bad to drain out. If you are boondocking in the woods, I don't see a problem doing like you did with the gutter extension. Now if you are in a crowded campground and everybody is doing that, it's a mess.
In some places draining gray water is prohibited due to wildlife, plants, etc., so pay attention and don't drain it where you're not allowed.
Also gray water that drains upon use is usually not offensive. Gray water that sits in a holding tank for a couple days reeks almost worse than the black water. So draining gray water upon use is not the same as emptying a gray water tank in the woods.
Our first pop-up had no holding tanks. In campgrounds we used the bath houses and washed dishes with the tenters. At the beach we had to be self-contained so we used a cassette port-a-potti and I attached a hose to the sink that drained into a portable blue tote. If you use a basin in the sink for dishes, you can also dump that into the black tank thru the toilet.
There are a bunch of folks here on the forum that never went camping at all until they bought an RV and will try to convince you that gray water is toxic waste. It's not. Use your best judgement and be courteous to those around you and more importantly those who will come after you.