Here's more info on hows my trikes setup.
The front BB7 disk brakes are controled by a tamden brake lever.
The single lever pulls both brake cables.
It can be a bit of a pain getting both brakes balanced so they work evenly after renewing pads/cables, but its not bad.
The only downside is there is a risk of burning calipersout/heat warping disk rotors on long steep twisty decents where you need to stay on the brakes to keep control. Normally you could rest one brake while useing the other.
But my Trice is stable with only one front brake working, if you expect it.
The gears are worked off bar-end shifters.
The back is in the standard place.
The front is on a spur made up of two bar-ends.
There's just enough room to get my hand inbetween the main handle-bar and the bar-end to get the brake lever if needed.
One thing you could do is use two bar-ends, one back one up, to move the handle-bar around three inches back.
But you may have to play around with angles to keep the lock the same on both sides.
Luck ..........