Dunno it this helps, but there is a plug and socket on the rear fender where you plug in the entire rear light set up. So swapping wires around is easy. If going with stock Triumph stuff you shouldn't need to do any soldering. If anything all you will need to do is rearrange the wires in the plug, and that's not difficult. The schematic is in the Bonneville manual and is easy to follow.
But I agree with TTbonnie. Now would be the ideal time to swap to something cooler.
