Simulating production load on IOT Core with 3k mock IOT devices using sigv4 mqtt, api requests and curl to upload files to s3 bucket

I'm looking to simulate production load on our system that has 3k iot devices connected to IoT Core using mqtt with sig v4 authentication, api requests being submitted to drive the device functionality which can drive the upload, via curl, of files and videos to s3 buckets. Currently we are looking at using custom scripts to simulate a mock mqtt device in conjunction with a load testing framework e.g. JMeter, but have concerns about being able to successfully scale it up to the 3k devices producing approx. 5 million mqtt messages and uploading 5 million 50kb files and 60,000 10mb files a day without having the test framework/ network being the bottleneck itself. Being based in eu-west-2 are there particular AWS based tools that can be used to simulate mqtt devices to this extent?