i would just test film exposed at a low asa and developed in a dilute developer
OR
if you can find instant coffee, sodium carbonate ( or bi carbonate to heat- force the water out of and covert to carbonate ) and vit c.
spike it with a few ( 10-15cc/100cc of coffee developer) of your favorite print developer
you can make a low contrast developer that you can stand ( 30-40mins? ) develop your over exposed film in, and it will turn out fine.

have fun !
john