We used to do time check to 80kts when flying Hercs off an unimproved strip. The NAV would start a stopwatch at the beginning of the takeoff roll and at eighty knots either say CONTINUE or STOP depending on the time taken. The timing was, of course, worked out well before the take off started and was usually around 12 seconds dependent on all the usual variables.
It worked well until you rolled into a boggy spot at 90kts!!
I can't see why something similar could not be done for RPT ops.
Regards,
BH.