We are using a similar approach for accessing historical block hashes on-chain in Relic Protocol. We store Merkle roots of chunks of historical block hashes in storage, and use zk-SNARKs to prove their validity.
For reference, see relic-contracts/BlockHistory.sol at 2ecb2ffdd3a450a8eb7c352628c2ef51ed038c42 · Relic-Protocol/relic-contracts · GitHub
This is already deployed on mainnet, and we’ll be releasing a developer SDK for integration shortly.