Multiple Day Run Times

We have a customer that builds large assemblies.  The welding of these assemblies spans several days.  Since the Bill of Material/Production Order Details only allow up to 23:59 for Run Time, we are entering fractional Run Units to plan hours >= 24:00 per operation. 

For example, if the planned hours are 250 hrs for a weld operation, we would enter 0.04 Run Units at 10:00 Run Time.

However, there are some cases however where we cannot plan the hours accurately due to run units only being 2 decimal precision.  Has anyone else run into this and have another solution?

Thanks!

LF