Thorn Audax

I'm pretty sure you can fit barends onto downtube mounts. I can't find it now but I seem to remember seeing a picture of it on this here forum.

you could use 'stash bars, they are designed to work with drop bar levers, I think - but then the levers will be at the furthest point forward on the bar. I've always fancied a set up like this:

I highly recommend this style of handlebar, it's much more comfortable than a drop bar if you never use the drop.

Here's an example of the Bridgestone which is almost identical to your Audax bar the 26" wheels.