Originally Posted by
WalksOn2Wheels
Another option is Arundel cages (the best cages) which have two sets of holes on most of their cages so that you can put one in a lower position.
Yet another option is
this nifty Shimano bit which is designed to move a bottle cage up to clear a BB moutned Di2 battery, but could also be used in the other direction, provided it clears your FD clamp, or that you have a braze-on FD mount.
OOOH! Both of those are great ideas, and the second one is exactly what I was thinking about making, thanks! I'm ordering that now, it'll be handy to have in my box even if it doesn't work.