My setup is for touring, not rando riding. But it should work just as well.

I have enough steerer tube on each of my bikes for a second stem. On some bikes I have a short stub of handlebar in that second stem to mount the bar bag bracket, but on one bike I used a short piece of PVC pipe to mount my handlebar bag bracket to the stem.

The bags I have have not been sold for several years, plus I spent several hours modifying the bags, so I am not highlighting the bags in this post, only the concept of a second stem.

In all three cases in the photos, I am running interrupter brake levers, since the bar bag bracket is not attached to my handlebars I do not lose any valuable real estate on the bars for computer, GPS, bell, etc.

In the first photo I used an adjustable stem, that allowed me to get the bag lower and also get the weight closer to the steerer tube which is the steering axis. I do not attach lights to the handlebar, I have dynohub powered lights on two of these bikes. But with the lower bar bag, I probably could attach a light above the bar bag if I wanted to.

ADDENDUM ADDED MUCH LATER:
Today my PVC pipe for my second stem broke. I will be looking for a discarded or cheap handlebar to cut to replace it. Fortunately I was less than two miles from home when it broke. Rode 54 miles today, so it could have picked a much worse time to break. I no longer suggest PVC pipe for that purpose.

I am looking for old posts where I suggested PVC pipe to make this additional comment.