Any tips for successfully submitting an h2o model?

Yes, it’s hardcoded in the R zip file routine load model which is part of model.R unless you’ve already overidden?

load_model <- function(){
 # Load a saved trained model from the file `trained_model.RData`.

 #    This is called by the server to evaluate your submission on hidden data.
 #    Only modify this *if* you modified save_model.

  load('trained_model.RData')
  return(model)
}