I've done this exact thing with my L28500 / L280. Consistent light colour failures while the normal colours remained fine. Sure, we could normally send them back under warranty but we were never reimbursed for the rolls and rolls of media (mostly cast) that got scrapped. I run Caldera with my printer, so I can't advise exactly on what should be done. But number one step is to check if your RIP even has a 4 colour mode available to create a new ICC profile for your printer. We then ran into another weird little thing. Our L280 wouldn't account for the correct use/non-use of the light colours. So when the light cartridges started nearing 15% left, we would get an error on the cartridge. Of course the thing was practically speaking still full. Our local HP dealer eventually told me to send it for a replacement when it happened. But that's not ideal.
If your RIP doesn't have a 4 colour mode for the printer, then hopefully you're able to turn down the transition curves from light to normal colours to near zero. So the profile will be built with CMYKlc in mind, but it won't ever get to use it.
Or you can increase the amount of light your machine uses, which does sound counter to what you're trying to achieve. But firing the heads more will keep them functional longer.
