Bulk auth clients userflow?

Hello I’m an operator of a very large hidden service.

Due to ongoing attacks with DDOS we are exploring the possibility of switching our userflow as the following.

Create our x25519 keys in advanced upon successful user registration and a human check the user is given the key and the link to the authenticated onion service.
Is there a better way to do this?
Will this help circumvent DDOS attacks against our service by rate limiting our user registration?