I am not sure if RPC is Thrift's greatest strength.
It excels as a data storage/interchange format, it is phenomenal at that.
Cassandra was one of the biggest known users of Thrift RPC and they have replaced it with an alternative RPC mechanism in their latest versions.
Why not just return Thrift byte array from a REST endpoint using a different content type, e.g.
application/thrift
or something like that?
That would give you access to the nice semantics of REST services but with a more compact data format than JSON.