I think you already answered your own question: the field type is just wrong. Why try to work around something of which you know it is causing the issues currently (and who knows what issues it will cost in the future).

Create a new field of the correct type. Write a fix script to move all existing data from the old field to the new and go through your catalog items where you are using it. Not fun work to do, but it will save you a lot of headaches in the future.