I finally took a pic of my handlebar ends. They're working great and I totally dig the available positions for my hands (and wrists).
The typical bar ends attach to the end of the existing bar which would take up about 20 to 25mm on either side. I didn't want to shorten the current length so instead, I used bar extenders from Control Tech here in the USA. The Terminator MTB extenders (with 22.2mm diameter) work pretty well and give just enough extra distance to attach most bar ends.
To install, all I did was cut a circle hole out of the end of the grips to make way for inserting the extenders. Once inserted they tighten easily with a 6mm hex key wrench.
The only issue I found is that they have to be tightened a few times to reach full grip strength. In other words, I tightened them, found them a bit loose the next day and tightened them again. After doing this 3 times, they're now really solid and I bought a second pair to have on hand just in case something goes wrong with these (I like them that much).
Here's the link to anyone who wants to try:
Control Tech offers two styles, "MTB" and simply "Plugs." Get the MTB as they're the right diameter. The Plugs are too large to fit inside the Halfbike handlebar tube.
As an extra bonus I found them on Amazon as an "add-on" item which means they were only $5 if I purchased $20 of other merchandise during the order. It's a promotional thing for Control Tech, I believe. Since I already had an order going, I got the extenders cheap!