If he is still in shed by then, I'd wait.
With a healthy snake, it can't hurt to try. They will either eat or not. Personally, I never offer while in shed. I feel their body uses resources during shedding, bodily fluids, etc. During digestion the body is also hard at work, needs the fluids, energy, etc.
Since your boy was heavily dehydrated, I'd give his body more time to recover before asking it to perform the double duty of shedding and digesting at the same time.
After that, you can offer once the week. If he still refuses, offer 2 weeks later. After that you may have to go to a smaller then usual "live" rat (with supervision !!!) Once you jump start their metabolism, they usually get so hungry that they will then accept F/T without to much fuss, given its presented at the right time (late, dark) and really warmed well, through and through.![]()