I would advocate for 100% but 10% is way better than 0%. I didn't have any on-call peers during my time in DoD so I'm unfamiliar with the structure for that arrangement, but very familiar with regular overtime stuff with DoD.
10% of time-and-a-half (15% of normal) seems reasonable for time that you are expected to be able to do your own thing but stay available. I negotiated 25% of normal pay for similar things.
24 hours of call at 15%, where they never call you, becomes a half day of pay. If you get a call, whether brief or using the whole 2 hour chunk, you're basically paid for a full normal day. This all feels just and reasonable to both sides.
100% of overtime rate doesn't make sense to me because then they're paying just as much as they'd pay to have you actively work the entire time.
