Hmm I think you should give the demo version for download. What I've read from OFP.info they have the demo island, maybe you can send them an updated wrp-file every 2 weeks or so.
The wrp-file and config.cpp/bin should have their own pbo in the demo version. So every time when we download the update for this island we would only have to overwrite the wrp-pbo. No hassling with opening the catintro.pbo and replacing the old wrp.
And when you add new objects they should too have their own pbo, and this pbo would be updated along with the wrp-pbo. So the pbo-files would be:
catintro.pbo --the major addon file
catwrp.pbo --only the wrp-file and config.cpp/bin
catobjects.pbo --new objects
*EDIT* well I was probably a bit confusing
, so please ask if you didn't understand my idea