Client – How can I query all OP_RETURN data starting at a specific block height (or hash)?

I’m working on a “light client” for the Identity Overlay Network (ION), and would like to know if there is a better way to get the OP_RETURN data needed to build state.

Currently I am iterating through all blocks starting at a certain height and then looping through each transaction and each transaction output to find the OP_RETURN signature I am looking for.

Is there a better way to do this by only requesting all OP_RETURN data? The bandwidth requirements to download all the block data would be a bottleneck for what I want to do, but I don’t think what I’m looking for is possible with the Bitcoin Wire protocol alone.