Yes, I agree with Nav. The peroxide should be a 1/10 soln and should only be used for the first initial clean.
Baytril is widely used and effective for turts. Either bathing and inj (or oral) and so long as dose per weight is correct, it will be fine.
Yes, sticking to one tmt is best. Personally I'd think for me I'd be doing the initial clean of wounds (even if they bleed and poss need a sprinkle of permanganate), then stick to baytril inj, dry docking and 2 periods of rehydrating/ eating etc in very clean water daily. And one soak in a baytril bath prior to dry docking for the night.
The girl I had out of the river, with a hole right thru her carapace exposing the flesh, responded most to dry docking...stressful tho that is for a turtle...and once there was a thin film of skin over the hole, betadine was used as well. With your one thats a huge amount of bone exposed for a turtle I'd be worried about her pain levels and the dog saliva and its incredible risk of infection in its victim Maybe the baytril baths need to be more frequent? Thats where I'd want a vets advice.....