Don't update the public record, let the next owner deal with it.

You can use the appraisal record for your listing like your realtor suggested.  No one will complain, especially, the next owner.  He/She will be happy to get more land or house.  You can get more money for this as well.  If you apply for the update, first, it is more work for you and you don't get any benefit since you are selling, second, the next owner will have to pay more property tax.  No one wins except your local government.  I will not cheat the tax, but I am sure that I will not voluntarily to tell them so that they can charge me more.  Good luck.