Dividing Plant and Mobile Costs

We are trying to look for a way to divide plant and mobile costs and electrical.  It seems that the Major Accounting Class is the only field Fixed Assets says we can't touch.  What they want to do now is remove the cat code mapping from the Fixed Asset to the Work Order, this means that each wo would have to have this field completed.  We have three sites and I do not believe they will all sign off on this.

Is someone else out there doing something different, we are looking for some ideas.

Thanks

Terri