Hi Robin first idea is to use the zero order flux increase but initially I will just save it all and process off line until I am sure it is robust. The drive on the obs PC is large an fairly empty.
Some late M dwarf stars flare quite often so I will start with them.
Reading up on the flares it seems the flux increase is higher in the U then B etc. going down to low in R.
I will use an IR cut filter to get as far as I can into the U band without contamination. Although IR cut filters seem to cut UV as well!