I can't offer any advise on raw, I feed BB. You can cut back on food intake since she won't be as active and use a kibble feeder where they have to work for their kibble and offer raw veggies as an alternative. Still take on walks but get a back pack for her to carry. Make sure the weight is balanced. I use soup cans, start with a small amount and increase the weight. Look at a treadmill (where I live you can find them on freecycle.com for free) and adapt it for a dog. Play while in the house, tug, ball toss, provide mental stimulation toys.
Taana n Beastley