What is the best way to pass a byte slice to a probe?

I am considering using tracing probes in a networking application and would like to pass packet data before and after encryption to the probe. In userland, these are just byte slices. What is the best way to pass those to a probe? I saw in the documentation that we can pass string slices but those have to be valid utf-8 and it seems like it would be unnecessarily computationally expensive to either serialize these bytes to JSON or hex once we get into number such as 5 million packets / sec. Would it be possible to expand the API to also allow passing a byte slice?