Allow an extra, optional variable to be passed to clone_node_save and clone_node_prepopulate for use in hook_clone_node_alter

I have a use case where I have an array of date fields on a node (from date repeat in Date API) and I need to add a button on the node edit form to convert each entry in the array to a new, identical node with a single date entry.

I looked at a few other modules that claim to implement what I'm trying to achieve such as http://drupal.org/project/date_repeat_nodegen and http://drupal.org/project/node_repeat but they all seem to be poorly maintained and there's a lot of outstanding issues around nodes not being cloned "cleanly".

I've used node_clone before in a few different projects and I think it does the job of duplicating a node quite well.

What I wanted to do was simply create a function that fires on submit that loops through the date array from my original node and calls clone_node_save() with a corresponding hook_clone_node_alter() function to make sure the date information on the new node is correct.

The problem is that right now all I have access to in hook_clone_node_alter() is the original node object, the new node object and whether we're in save-edit or prepopulate mode.

The extra bit of information that I'm looking for is of course a counter or similar so I know where I'm up to in my loop and can add the correct date to the new node. Adding an optional variable that could be passed to clone_node_save to hold external paramaters and passing that to the hook function should be enough to get what I want.

I figured that worst-case I could pop dates off my original node as the new nodes are being created but this doesn't feel like it would be the "best" way to go about this.