Quoted from P2K:Is it as simple as putting a resister(s) at the beginning of the GI strings?
They would get very hot but yes this is an option. You can use a bridge rectifier to knock drop @ .6 or 1.2 volts depending on how you wire it. You can put 2 or more in line to drop another 1.2 volts for a total of 2.4 volts.
ebay.com link: 2Pcs 1000V 50A Metal Case Single Phase Diode Bridge Rectifier KBPC5010 USA