Unless you really work hard to choose the most expensive options at the most expensive restaurants every time,
DDP will likely not save you money. The best you can hope for is to break even. I'd go OOP for two reasons: money and flexibility. I feel like the benefit of a mother-teen trip is that you can do what you want when you want. Park hoppers will facilitate that. You can get off Thunder Mountain and say, "Hmm, I wonder how that compares with EVerest," and go right then to check it out if that's what you want. A lot of dining reservations would get in the way if that-- unless dining is really important to you, but you said you were 95% rides. I'd choose one, maybe two, memorable dining experiences and do fun, in park counter service for the rest of your meals.
I think PH will help you maximize the number of rides in your case. Know what park you will start in each day-- probably one day for each park except AK-- and make mid-morning FPs for that park. Then, you can decide to stay in that park or hop once you've done everything you want. I don't think you'll need a lot of time in DHS, for example. There's only a handful of actual rides open right now. Using RD and FP, you will likely be done there by early afternoon. Enjoy!