IMO when people talk about a "rebound" effect, what has really happened is that using T3 has allowed them to consume higher than maintenance calories and still lose weight or maintain it, due to the increase in their basal metabolic rate caused by T3.
The thyroid really shouldn't take long to get back to normal, maybe a week or two.
So I think the main thing is to consume a reasonable amount of food and do cardio.
Sure you can use clen or eca if you want, but I think the whole "rebound" thing is overblown.