With your extreme weight reduction process I see no need for any cup holder, etc. Just pull it and make a plate from aluminum (thin) or lay up some carbon fiber if that is you thing. As long as you don't require the cig lighter for accessories all of it is not needed. I am a bit of a weight weenie but I will not spend money on titanium bolts for my bicycle to save a gram. I would rather ride for 50 miles and lose a few ounces.
A resealable water jug works without a cupholder. I almost always stop during a 5hr drive to do something. Actually you can tuck a bottle between the seat and frame.