Anyone pay excess hours over comp time limits?

This may seem counterintuitive, but I have been tasked with figuring out how to do the following for a union. Assume an employee is exempt and has a maximum comp time balance limit of 80 hours. They enter time into Time and Labor, normally their time is entered all as REG, anything in excess goes into comp bank, and is lost after 80 hours. Now due to retention issues, these exempt employees are being requested to perform additional work beyond their weekly 40 hours to backfill other positions, but they refuse unless they can be paid for any hours that would be in excess of their 80 hour limit. All discussion aside, I believe the easiest way to track this is with a TRC of BKF for backfill, which will then process over to Payroll to be paid just like their REG pay, but tracked separately. So these are the requirements.

1. Create separate tracking BKF to track the backfill hours.
2. Any REG or BKF hours go into their comp time toward their limits.
3. If they exceed their 80 hours, the time should be paid out at 1.5x their regular rate of pay if they are BKF hours, otherwise they are to continue to be lost.

So for examples
If an employee has 70 hours comp time balance and puts in 40 REG and 8 BKF, it will increase their comp time balance to 78.
If an employee has 80 hours balance, and puts in 44 hours REG and 8 hours BKF, they will lose 4 hours REG, and be paid 1.5x their rate of pay for BKF.

Does anyone pay out over their comp time limits, or have a regular cutback where you perform payouts, etc?