You don't want to stop insulin cold turkey. For a strong remission, we slowly reduce the insulin dose to zero. After a week in normal numbers on 0.5U, you would go down to 0.25u and then 0.10U. I know it must be tempting to stop and be done with shooting and testing, but you are on the last stretch now. Fingers crossed.
You are testing enough and he is in safe greens. If he drops below 50 at any point, he earns a dose reduction. If you find your vet doesn't support this, maybe just avoid discussing Tango's diabetes with him? Or fib saying you stopped the insulin. Some of us have done that when our vets don't understand.