It is correct how you pass options from jsreport to aws sdk.
I see in the docs
https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html
That it could work with httpOptions.proxy
Although elsewhere I see mentioned other approach
https://stackoverflow.com/questions/66969381/how-to-configure-nodejs-aws-sdk-using-s3-client-library-with-proxy
It looks like the more complex approach benefits from connection pooling, which shouldn't be necessary in this case. Does your config work? Any errors?