How to monitor high voltage capacitor bank?
A 1000:1 voltage divider night be better. Make sure your series resistor has an adequate voltage specification. If you don't want to buy high voltage resistors, then often what folks do is put several ordinary ones in series. You are unlikely to run your cap bank down too quickly with (say) 10 off 10Meg resistors in series.

With any cap bank, it's good practice to have a resistor permanently attached to bleed the charge off when unused.