The question is would that goal be acceptable to you. If both sides came together and agreed that ever year they would shrink spending compared to GDP until it reached 19% would you find that acceptable.
As far as the refund thing. Sure I don't have a problem with that, although if evenly divided between all sources (personal and business) I doubt it would ever be noticeable.
No, the question is how we achieve that goal. Good intentions are squat, I want details.
By the way, you do not want to set taxes at 20% of GDP, you want to set revenue at that level.