Hi Tom, I think you are on the right path. Provided your model is already on S3 and packaged as tar.gz file you can just use the deploy() method to deploy the model. To get predictions you can use predictor.predict, as you have already pointed out.
This notebook by @philschmid should be useful: notebooks/deploy_transformer_model_from_s3.ipynb at master · huggingface/notebooks · GitHub 1
Hope that helps, let me know if there are any questions.
Cheers
Heiko