please add a jumper to disable auto reset

one thing that would work pretty well would be to use one of the FT233RL bitbang pins instead of the DTR pin. Then you'd use libftdi to twiddle that pin to reset the Arduino instead of relying on DTR. Another nice thing is that a capacitor isnt necessary anymore. Disabling the pin is pretty easy, just use MProg or set it to an input via libftdi when not resetting in the IDE