I'm sorry, I don't know much about excess fluid and VBAC. I think a good move is to ask a lot of questions. So if they recommend doing any medical interventions ask about the pros and cons, what alternatives there are, and whether doing nothing is an option. If they recommend a cesarean, ask if they are recommending it because you have a prior cesarean or if they would make the same recommendation for a mom with an unscarred uterus/FTM. That way you can make an informed decision and hopefully feel confident that it was the right move.
HTH and GL!