Would it be okay to use the bondo and cloth ( that they use onboats) in the shower, rather than taking it apart and putting it underneath? Will it work for a little while.

Is the floor cracked next to the drain? The problem with your solution is that you'll still have the same problem. And that is a shower floor that flexes and gives because at the time of installation it was never bedded in. Will your fix work for a little while? Perhaps!
But when you step into the shower you will be putting a strain on the same section you patched.
Good luck, Tom

Tom what is the going rate to have the bottom removed and "bedded" and then put together again?

Tom what is the going rate to have the bottom removed and "bedded" and then put together again?
It depends upon location, Wage scale, union or nonunion labor, etc. I've retired for over 20 years so I don't know the dollar amounts any more, I'll ask some of the experts to answer but your best bet would be to get three estimates and go with the on you're nost comfortable with.
Good luck, Tom

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