Customizable "Value of Hours" per opportunity

At our organization, we value the hours of our board members at a higher rate than our regular volunteers because of their expertise that they provide. However, with the "default value of one hour" in the general settings, if we change the value of hours while importing our board member's hours, it will historically change the value of all of the hours. We believe their contribution is different than most of our volunteers and would like to be able to value it as so, if possible. It seems like an easy fix for this would be adding the "value of hours setting" to each opportunity, so that there is still a "default amount", but if you wish to customize a particular opportunity to be something more specific you can.

Another way to fix this would be to allow an additional field of "Value of Hours" when uploading historical hours.