One idea off the top of my head is to use Lot Tracking, and have the Lot Number represent the sizing.  come up with a "standard" format.  Like ###0.00.  I would certainly suggest giving this a test, since changing item valuation from what you use today to Lot Tracking (it is an item valuation method); will be more work.  

Yes... transforming stock can be difficult with this strategy, but DSD has an enhancement that allows a BM recipe to have an item as a component of itself.  That way, if you resize (cut) the stock, you could use BM to consume one lot# and add to another.