Honestly I think you're just doing it wrong. Messing with PDF's is probably one of the coolest built in features I know of, and with Markup etc in Preview it's super easy.
Be careful of PDF's with built in broken fields though, in which case I just add a text field on top if it's easier.
Be careful of PDF's with built in broken fields though, in which case I just add a text field on top if it's easier.