[otrs] PendingDiffDate only during Working Hours?

I'd like to configure the pending date to only count working hours. So if I have a default pending duration of 2 days and I set a ticket as pending on Friday I want it closed on Tuesday not Sunday. I have looked high and low and thus far he only seen other folks asking about this type of functionality but can't seem to find anything actually implementing it. Additionally, I'd like to set tickets to close at a certain time of day (say 17:00) as opposed to xx:xx (time of response to ticket) + yy:yy (pending duration). So if the pending duration falls at 12:34 it is adjusted to next 17:00. I think this is probably a generic agent function but haven't been able to figure out how I'd go about it. Thanks