I don’t think you are going to find any traditional bar ends with clamps that won’t take up at least 1/2” on each side.

One option may be to look at some of the ergon options that have the bar end integrated with the grips. Since the ends don’t need their own clamp, they add very little width.

The other option is to find whatever bar ends you like, and get a new, wider bar to accomodate the extra stuff on the ends. Of course, once you have the wider bar, I would first try the grips at a wider position and see if you like it (if you have not done so already).