Patterns for secure off-chain storage and retrieval of EIP-712 structs

Many useful resources have been created for implementing logic for utilizing EIP-712 signatures, e.g. EIP-2612 style permits or Compound-style voting delegation.

However, very few resources exist on best-practices for off-chain aggregation and storage of these signed structures, along with how these meta-transactions should be securely called via relayers.

E.g. in the case of a EIP-2612 style permit, where I want to have a relayer permit and transfer another user's token, what are common patterns for:

  1. Storing the signed EIP-712 structs off-chain
  2. Invoking a relayer to batch these meta-transactions together (e.g. via GSN)