Cylons would require diplomatic vessels in order to establish ties with other Cylon races... or other "non-human" races, as you have mentioned Z.
Z... Do you mean the small Attackstar models from Kyogre12's mod (if so, the texture was pretty crappy so I imagine this will be changed) or the actual original saucer basestars? I think that if you meant the latter, may not fit as the old school basestars were heavy attack ships (although obviously their functionality could change) - perhaps you could add some limited weapons to the diplomatic ship? Would need to use the texture from Larkis' mod for the old school ship as it was pretty spot on.
I am currently working on a group of scenario's that takes place after events of the new series. Basically, what happens to the Cylons after they leave the earth solar system in the rebel basestar - a pure Centurion race. It leads up to another confrontation with humans of Earth in 2,300AD, considering that we know that the human race follows a very similar technological evolution to past societies - "this has all happened before, and will happen again".
In the time period between 150,000 years ago where the series left us, to 2,300AD, the Cylons face wars with Cavil's remnant forces, Hypercorp and Vasari, all in the lead-up to re-establishing contact with the Earth system which has developed in a similar way to the 12 colonies.
Cylon development is represented in the form of new ships i.e. Boomer class, new star bases, advancements in Centurion design and research, and other new and advanced cylon basestar models which is reflected in ZombieRus5's mod.