My hat is off to you, mama!!! At seven, my autistic son (now 33) was starving himself rather than try any of the "allergy food challenge" foods I offered. We took a family cruise when he was 19, and he'd outgrown most of the noise problems, but there we were in Ketchikan Alaska shopping for the right bread, the right peanut butter, the right jelly because a steady diet of hot dogs cooked the way he liked them was not available, and all dessert all the time was not available either...
I'm sure you know, prepare for any and every tiny little thing. My son loved that cruise, and still talks about it.