I might give this a try, but the tiny 85 looks like a fantastic fit: it has TWI and the three other available pins.
TWI is on PB0 and PB2, leaving PB1 (PWM), PB4 and PB3 available (PB5 is /RESET).
Nick's diagram and sketch use Arduino pins 1 (TX), 3 (PWM) and 10 (PWM) to drive the VGA output, but I only have PB1 available with PWM on the tiny.
From what I can see, the sketch doesn't make use of PWM, so I'm wondering if the tiny would work to drive VGA. This would make for a very small "controller" and the whole setup could be connected to the master controller via a 4 wire cable, including power.
Thanks for any ideas.