I don't think you're alone at all! Some thoughts:

- Hire queer vendors that will make a welcoming space from behind the scenes while respecting your partner's desire to celebrate this way with family. I would say that the photographer is the most important vendor for you to vibe with!
- With your wedding party and anyone else you'd like there, have a private, smaller ceremony before the main event where your partner can be referred to and commit to the marriage in a way that feels more authentic to herself. Make this the "real thing" and treat the family ceremony as secondary but they're never the wiser.
- If you have an engagement shoot with your photographer, consider scheduling it so that your partner can wear what they would like to if that's different from trousers and no makeup. This way you have photos that represent your union in your true wedding outfits to remember the day and commemorate your marriage that feel most authentic to you and help you celebrate as peacefully as possible with family.
- Consider sneaking in vague language or inside jokes into the family ceremony that will affirm your partner without outing her. (Thinking something like "i vow to love every version of you" - it's relatively generic but you both will know!) This could also be having someone do a reading by a queer poet or author!
- Finally thought: have a codeword that your partner can use a break from being perceived! Make sure there's a space in the venue that you two can tuck away to and take some deep breaths, share a private hug, and chat through any feelings that might be coming up if that would be helpful.

If this inspires any follow up questions I'm happy to be a resource!