The basic t4 ar'kif has it's own model, and the t4 ar'kala refit has a unique model as well (and, obviously, the parts are interchangeable for customization purposes).
When browsing the shipyard, selecting the t5 ar'kif (tactical carrier warbird retrofit), you have a dropdown menu that allows you to view it as one of three options: Ar'kif, Ar'kala, and "Unique" - however, the "unique" option is the exact same as the ar'kif model.
So how about it devs, perhaps the t5 can get a bit of customization added? Maybe a slightly more pronounced hangar bay, considering it's the carrier variant?
-Remove the 'middle' engine at the back of the hull.
-Make the two side engines slightly larger.
-Put a through and open hangar bay that goes down the middle of the ship (openings on the back where the middle engine would be, and on the front below the 'head' of the ship), with visible forcefields like the atrox has for it's two hangars.
-Give it quad nacelles instead of dual (each wingtip would have one nacelle on top and one on bottom, meeting at the center where the two wings come together) to portray a beefier engine system needed for the added mass of a carrier.
-Give the singularity exhaust ports a slightly different look than the other variants.
-Change the head of the ship to give it a visible weapon emplacement for the singularity beam to emit from, and room for the hangar underneath the head (so the head does not obstruct fighter launching).
-Make the wings sweep forward a little bit more, to give a more aggressive look.
And, of course, all these options would be interchangeable with the ar'kif and ar'kala variants at the ship tailor.
T1 you have the original Romulan BoP and the T'Varo refit. At T5 you get the T'Varo Retrofit. With no parts choice at all.
T2 you have the Dhelan and it's refit. At T5 you get the Dhelan. Refit parts if you own them and a few wing choices.
Same for Mogai, D'Deridex and Ha family (Haakona is a member).
A long time ago Cryptic tried to sell a skin for T5 ships, practically nobody purchased them so they where rolled into the Fleet System.
I'm sure the Fleet Ar'kif will have a Fleet skin for the Unique option but don't expect a 3rd model. Your never going to get Federation levels of customisation but you've already got better than the Klingons on most ships.
I was once DKnight1000, apparently I had taken my own name so now I'm DKnight0001. If I ask you a question it is not an insult but a genuine attempt to understand why. When I insult you I won't be discreet about it, I will be precise and to the point stupid.