If you are not runnig a relay to the fuel pump to get dirrect battery voltage you can try to use a voltage stabilizer to maintain constant voltage regardless of input. Used this one before and worked great even with the generator. Headights dont flicker with voltage or engine speed change. Just bright all the time. Should make the electrical items last longer, as it also controlls spikes in system voltage.
http://www.jacobselectronics.com.au/