Salvaging dealer mistake - warranty/battery question

Looking for advice. Bought a 2014 Prius v in May, 51K miles, for $14,800 plus tax and fees. Part of why I bought it is that the dealership said they would "throw in" CPO status (1 year bumper to bumper, 7 power train). They also told me that Toyota CPO coverage had just been amended to include an 8 year hybrid battery warranty from MY date of purchase, rather than from first use. (3 different staff members confirmed this to me.)

Last week (3 months later), I found out they were either lying or incompetent. It's not CPO, and was 8 months too late to qualify for that. I've been trying to get a hold of someone helpful there for the last week, and finally got through today. They offered me 3 years B2B (platinum extended warranty, I assume) because they can't purchase two separate warranties to cover the B2B and the power train, but I told them that I still wanted what I was offered in terms of 8 year battery coverage. He said he's not sure if/how they can, and would look into it. Called me back to let me know I'd have to wait until Monday for an answer re: battery, and - when I asked - said he could just do 5 year B2B warranty instead.

Question is: would you take the 5 year platinum extended warranty? Should I hold out and try to get the 3 years extended warranty plus 8 years of battery replacement? What's the 7 years of power train coverage worth? Is there something else I'm missing here? It seems like the battery isn't that likely to fail, and would cost around 2K with labor from a place like Green Tec (or prob other non-dealer shops). I like that the B2B warranty includes most other things besides the battery, plus 5 years roadside assistance, substitute vehicle coverage during repairs, etc. Would you hold out for the battery? Thanks in advance for any helpful advice.