I think the easiest thing to do, while taking into consideration the childs gender ID, as well as the possibility that the parents may not be supportive or worse, is to avoid pronouns whenever possible. Since the kid has a gender neutral name this should be fairly simple. Im sure "Randy" would LOVE to be called she and her, but if you avoid pronouns as much as possible you will at least be lessening the sting that he and him leaves. Not using pronouns seems like a hard thing to do, but the important times will be when Randy is present, and if Randy is right there in front of the teacher she can just use Randys name or say you.
Rather than say "Ok class Randy is going to show us his/her picture now" just make sure you phrase things so you can say "Randy its your turn to show us your picture." It does get tricky when your trying to be purposeful about pronouns but it can be done, and really every time you avoid using the pronoun that the kid does not ID with your making life a little easier.

my daughter is adept at handling pronouns. She has been raised in an aware and Present household/family. I have dated male IDd butches and FtMs most of her life. Her language is very inclusive, where ever she is, whomever she is addressing. I am rather proud of her. And she teaches others to be so as well. She doesnt think twice about informing someone their language/labels/pronouns might be insensitive or even hurtful. And she does so in a way that doesnt make others defensive.

btw...I have found out that the principal is aware of Randy's gender ID. She really likes how my daughter has handled it. I give this principal alot of credit because she is very aware and inclusive in many regards.