You need an 1" of it to keep it from deflecting (unless you stress the
hell out of its support), it will change shape no matter what finish
you put on it, work running accross the grain will scuff it and spoil .
Put some fixturing on it and as it (your substrate) changes shape it
will distort the fixturing. Flatness is critical, you won't get it with
wood.
If no precision work is expected use it, give it a shot.