So your plan is to engrave all 60 words onto the plate?
How is the user supposed to remember which of the 60 words are the seed? Won't that then necessitate that the user then have some special method of working out which of the 60 words are actually their seed? And how would they back that information up?
It would seem that the methods employed by
CryptoSteel or
Billfodl whereby the user is provided a bunch of individual letters which they arrange themselves... or
Blockplate, where the user needs to use a metal punch to encode the words themselves removes the "trust" part of the equation.
There are more examples of similar products listed here:
http://bulletproofbitcoin.com/The math "sort of" supports your method... but the problem is that you're effectively shrinking the search space from 2048 to 60 words... which is a massive reduction... and then asking people to trust you. That could be the very hard part... People in Crypto are VERY suspicious of everything