Creating a port as plugin for multiple other ports

[Matthew Pounsett]

Pardon the cryptic subject line.  I couldn't think of a more concise way to describe what I'm working on.

I'm working on building a port of mod_gearman, a monitoring plugin for Nagios and Icinga.   Since the plugin might modify icinga or might modify nagios, it has different possible install locations for some support files, and different possible users as owners of those files.

The question I have is about the best way to approach this.  Is this something that crops up often enough for there to be a standard (or even just preferred) method?  The two that come to mind are:
1) create two different ports (icinga-mod_gearman and nagios-mod_gearman).
   I don't particularly like this one since it requires maintenance of two different ports.
2) use options to select which system is being plugged into.
   It's not clear to me whether it's considered good practice to define options that are mutually exclusive, or whether reading in of the options file would be too late in the process for defining dependencies.

Are there other options here?  Any guidance on the best route to take?  Are there existing ports which are in the same situation that I can crib from?

Thanks for any pointers.