401 Asking for a member's pledges to my campaign

I’m writing an external website which will interact with users differently depending on which tiers they’re subscribed to on my campaign.

After getting an OAuth2 token on my user’s behalf, attempting to fetch their membership details from GET /api/oauth2/v2/members/<memberId> (with their Token in the Authorization header as a Bearer token) I am getting back a 401 from Patreon.

According to the API, I need the campaign.members scope to look at this endpoint, but I don’t want to include that scope in my authorization since I only want to know the membership with my campaign.

Is there a better way to fetch the titles of the Tier’s that the user is subscribed to? I don’t want to ask for the campaign.members scope from them, because I’m only interested in their pledge to me.