Data group URIs matching & redirection to external sites

without understanding the real nature of the patterns and whether the 1, 2, 3, etc is actually part of the URL strategy or not, it's hard to give a solid answer. But updating a file as an external data-group is "easier" than updating an internal data-group or a policy. One thing I'd recommend is limit how much you actually put in the data-group though. For example, if https://marketing-site.com is consistent, there's no reason to put that in the data-group since that will only take one entry in the iRule. The same is true for the /customerX, that'll be in the request so you can just read and copy that in a single reference in the iRule.

HTTP::redirect "http://marketing-site.com[URI::path]/$product_info_from_datagroup"

or something like that...