I've got a seat bag on my GF Mamba...it's medium size, about the length of a cell phone and holds all my must have cycling needs (see pic below).

I'm getting ready to order a taillight for the bike because I'm making the move to road cycling. The problem I'm having is there is no place to put the taillight...there isn't room on the post above the bag and their isn't room on the post below the bag.

So, what's my best option to solve this problem?

Thanks for your help!

TripleB67