Yeah, so revisiting this idea after I actually bought and have been using my trekker bars.
Not gonna do it. Here's why. First... I finally realize why everybody with trekker bars has them angled the way they do (the rear loop significantly lower); it's so your wrists are at a natural angle when you're grabbing the outer loop - much like acutal MTB bar ends.
With my bars in this configuration, plus the addition of a handlebar bag (cheap, not mounted low enough, but what I'm sticking with), I can rest my arms on the bars without having to have extensions out front. My arms aren't horizontal to the ground, but then again, I'm not a tri-athlete trying to reduce that last 0.4% of wind resistance so I can finish a 100 mile race 2 and a quarter seconds faster.