It is not a good long term plan, and very few people actually do trade fish in when too large. So you have a decision to make. Do what you want, and not particularly care about the fish, or about success (since there is risk involved), or about whether you will lose the fish to disease....or decide on a sustainable long term stocking list for your tank. I've seen and worked with both kinds of people, and to each their own.
Invariably, people will say "oh yeah, I did it and it was great" and they ignore the fact that a lot of people have experience to the contrary. I have a lot of experience with tangs, and I would say while it might work short term, it will not be a long term option...and the potential for losing the fish and perhaps ALL your fish is a reality.
So you decide. Ultimately, it is up to you, but remember many have failed rather dramatically and the fish pay the price. It is NOT the best choice for those fish long term. Of course, it is "not the ocean" but if that is your rational, then I suspect you wouldn't be asking at all.
People don't say no to rain on your parade, people are actually trying to help you succeed, and select fish that are likely to survive long term and thrive in your size tank. Sometimes that means having the discipline to know you shouldn't keep certain fish.